| Power Classification | 7P reclassified as 8P in 1951 |
| Introduced | 1933 – 1935 |
| Designer | Stanier |
| Company | LMS |
| Weight – Loco | 104 10cwt |
| Tender | 54t 13cwt |
| Driving Wheels | 6ft 6ins |
| Boiler Pressure | 250psi superheated |
| Cylinders | Four – 16 ¼in x 28in |
| Tractive Effort | 40,285lbf |
| Valve Gear | Walschaert (piston valves) |
One of Stanier’s first tasks on becoming CME of the LMS in 1932 after being head hunted from the GWR was to set about production of a really large engine for the West Coast route. At the time there were 70 Royal Scot 4-6-0 locomotives in service which handled the principle services between London and Glasgow so there was no pressing need for to add to the stock of express passenger engines. The Scots were however being pushed to their limits and Stanier concluded that the task when hauling the 500 ton Ango-Scottish expresses demanded something with power in reserve. He also thought that a new locomotive should have the capacity to cover the 401 miles between London and Glasgow without the need to change engines at Carlisle. Interestingly Gresley was taking a similar approach with Pacifics on the London & North Eastern Railway.
The first two of the Stanier pacifics, 6200 and 6201 appeared in June 1933 and they included several new features to LMS practice, including se of a taper boiler and low temperature superheater. These features came from Swindon where Stanier had been working as assistant CME before 1932 having started his working life as an office boy there in 1891. He went on to become a Fellow of the Royal Society in 1944 when he was elected as only the third locomotive engineer after Edward Bury and Robert Stephenson to receive that honour. This was the year after he was knighted.
These first two were initially based at Camden and Polmadie for working the 400 mile Euston-Glasgow through workings. They were found to be difficult to operate because of the crew being unused to the larger boiler, varying coal quality (which was not a problem on the GWR) and a problem that Stanier identified with the steam circuits. Apparently the GWR King class suffered from the same steaming problem as the Princess so Stanier informed Collett to let him know what he had found. Collett never acknowledged the letter from Stanier. Stanier decided that the GWR degree of superheating was not suitable for the LMS so the boiler was modified with a new 32 element superheater, which dramatically improved the engines.
 |
King class introduced by Collett in 1927 |
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Princess Royal class introduced by Stanier in 1933 |
Ten more locomotives numbered 6203-6212 were built in 1935, and the Princess Royal engines proved themselves to be greatly superior to anything which had been previously seen on the LNWR main line.
In June 1934 6200 The Princess Royal hauled a test train of empty coaches and a dynamometer car weighing 470 tons from Crewe to Glasgow and back – a round trip of 490 miles. A comparison of the times allowed for the Mid Day Scot and the actual times achieved by 6200 are shown below.
|
Distance |
Mid Day ScotTime |
6200 Time |
|
| Crewe-Lancaster |
72 miles |
84 min |
71 min 38 sec |
| Lancaster-Carlisle |
69 miles |
83 min |
68 min 24 sec |
| Carlisle-Carstairs |
73½ miles |
89 min |
69 min 11 sec |
The most important feature was however the fuel economy. The coal consumption for the round trip averaged 52.6lb per mile or a total of 11½tons in total. It works out at 2.88lb per drawbar horsepower. This was almost the same as achieved by Castle class Cadicot Castle in 1924. The difference being that the Castle was working to their normal schedule whilst the Princess was worked hard.
In November 1936 6201 Princess Elizabeth ran a proving trial for a tentative six-hour timing for the 401 miles between Euston and Glasgow. It did not materialise because of the increase in weight of the train formation, but 6201 improved on the timings, particularly southbound. The result of travelling at high speed was that coal consumption increased. A Princess class hauling the Royal Scot had previously recorded 2.86 lb/dbhp hr whereas 6201 on the trials needed 3.68 northbound and 3.48 southbound.
One of the notable features of the Princess Royal class locomotives was that the performance did not deteriorate as the engine spent longer in service between overhauls. An example of this was with 46210 Lady Praticia which having cover 98,977 miles since its last major overhaul achieved a coal consumption of 2.98 lb/dbhp hr whilst working with a dynamometer car attached. This would have been an excellent performance from a recently overhauled locomotive.
In June 1937 a determined attempt was made to break the world speed record of 112½mph but this was done using a Princess Coronation or Duchess class locomotive.
46202 was ordered as the third of the original engines, but it was built as an experimental engine which differed radically from others of the class. It used a larger 40 element superheater to give a higher steam temperature, more suitable for turbine use. This boiler was also domeless as would later be used for the second batch of the Princess Royals. The continuous exhaust of the turbine, rather than the sharper intermittent blast of the piston engine, also required changes to the draughting and the use of a double chimney. In place of the cylinders and motion the engine was propelled by turbines, a large one on the left hand side for forward motion and a small one on the right hand side for reverse running.
It was constructed with the aid of the Swedish Ljungstrom turbine company and entered service in June 1935 on the London–Liverpool service.
It was the only successful turbine driven locomotive to be built in the country, and it was known as “The Turbomotive”. Many snags were encountered and it spent a lot of time out of service undergoing modifications, but when it was in service it was a very good engine and performed work equal to that of others of the class. In 1952 it was rebuilt as an ordinary engine with four cylinders. In this form it was named Princess Anne. Unfortunately, it had a tragically short life, being damaged beyond repair in the accident at Harrow on the 8th October 1952, only a few weeks after appearing from Crewe. It was towed to Crewe Works where it remained until officially deleted from stock in 1954.
46205 was rebuilt in 1947 with two sets of Walschaert valve gear instead of the four on the other engines. The inside valves were operated by rocking shafts. It was converted back to normal in 1955.
Each locomotive was named after a princess, the official name for the class was chosen because Mary, Princess Royal was the Commander-in-Chief of the Royal Scots. However, the locomotives were known to railwaymen as “Lizzies”, after the second example of the class named for Princess Elizabeth who later became Queen Elizabeth II. Later examples of 4-6-2 express passenger locomotive built by the LMS were of the related but larger, Coronation Class.
Number in Service.
| Built | Withdrawals | No. in Service | ||
| BR Numbers | Quantity | |||
| 1933 | 46200-1 |
2 |
2 |
|
| 1935 | 46202-12 |
11 |
13 |
|
| 1936-51 |
13 |
|||
| 1952 | 46202 |
1 |
12 |
|
| 1953-60 |
12 |
|||
| 1961 |
6 |
6 |
||
| 1962 |
6 |
0 |
||
- 46202 was rebuilt in 1952 back to an ordinary steam engine but withdrawn shortly afterwards following the Harrow rail crash.
Allocation of locomotives in service as at 1st of January.
|
1948 |
1950 | 1955 | 1960 | 1961 |
1962 |
|
| Camden | 1 | 1 | 1 | 1 | ||
| Carnforth | 2 | |||||
| Carlisle Kingmoor | 1 | |||||
| Crewe North | 12 | 5 | 7 | 5 | 5 | 1 |
| Edge Hill | 7 | 5 | 4 | 4 | 1 | |
| Polmadie | 2 | 2 | ||||
| Rugby | 1 | |||||
| 13 | 13 | 12 | 12 | 12 | 6 |
- The only locomotive not allocated to Crewe North was the turbine engine 46202.
Accidents and Incidents
- On 21 September 1951, locomotive 46207 Princess Arthur of Connaught was hauling an express passenger train that was derailed at Weedon, Northamptonshire due to a defective front bogie on the locomotive. Fifteen people were killed and 35 were injured.
- The 08:20 Liverpool Lime Street to London Euston passenger service consisting of 15 coaches hauled by a Princess class Stanier Pacific began to de-rail south of Weedon, Northamptonshire, on the West Coast Main Line south of Rugby, at a speed of 65 mph and finally crashed, killing 15 people and injuring 35 more. The footplate crew survived and protected their train in spite of being severely shocked.
- The accident enquiry, conducted by Lt Col G R S Wilson, found the track to be in good condition and the speed of the train not to be excessive. However, this was the first trip out for the locomotive, 46207 Princess Arthur of Connaught after its bogie wheelsets had been swapped round. The enquiry concluded that the derailment was caused by an excessively tight bogie axlebox. The location of the collision was close to the signal-box at Heyford south of Stowe Hill tunnel.
- On Friday, 21 September 1951 the 08:20 Liverpool Lime Street to London Euston passenger service consisting of 15 coaches hauled by 46207 Princess Arthur of Connaught began to de-rail south of Weedon, Northamptonshire, on the West Coast Main Line south of Rugby, at a speed of 65 mph and finally crashed, killing 15 people and injuring 35 more. The footplate crew survived and protected their train in spite of being severely shocked.
- The accident enquiry found the track to be in good condition and the speed of the train not to be excessive. However, this was the first trip out for the locomotive after its bogie wheelsets had been swapped round. The enquiry concluded that the derailment was caused by an excessively tight bogie axlebox.
- On 8 October 1952, an express passenger train overran signals and crashed into the rear of a local train at Harrow and Wealdstone station, Middlesex. Locomotive 46202 Princess Anne was one of two locomotives hauling an express passenger train which crashed into the wreckage. A total of 112 people were killed and 340 were injured. The locomotive was consequently scrapped due to damage sustained.
- The Harrow and Wealdstone rail crash was a three-train collision at Harrow and Wealdstone station in London during the morning rush hour of 8 October 1952. 112 people were killed and 340 injured (88 of these being detained in hospital); it is the worst peacetime rail crash in the United Kingdom.
- The accident accelerated the introduction of Automatic Warning System – by the time the report had been published British Railways had agreed to a five-year plan to install the system that warned drivers that they had passed an adverse signal.
- The collisions involved three trains;
- The 7:31 am Tring to Euston local passenger train – 9 carriages hauled by a steam locomotive (LMS Fowler 2-6-4 tank engine running bunker first 42389) – on the up fast line
- The 8:15 pm Perth to Euston night express – 11 carriages carrying approximately 85 passengers hauled by a single steam locomotive (46242 Coronation Class 4-6-2 City of Glasgow which was repaired) – on the up fast line – this train was running about 80 minutes late because of fog.
- The 8:00 am express from Euston to Liverpool and Manchester – 15 carriages carrying approximately 200 passengers, double headed by two steam locomotives (Jubilee 45637 Windward Islands and Princess Royal 46202 Princess Anne both of which had to be withdrawn)- on the down fast line.
- Sequence of events
-
-
- At around 8:17 am, on 8 October 1952 the local train had stopped at platform 4 at Harrow and Wealdstone station, approximately seven minutes late because of fog. Carrying about 800 passengers; it was busier than usual because the next Tring -Euston service had been cancelled. As scheduled, it had travelled from Tring on the slow line, switching to the up fast line just before Harrow and Wealdstone to keep the slow lines to the south of the station clear for empty stock movements. At 8:19 am, just as the guard was walking back to his brake van after checking doors on the last two carriages, the Perth express crashed into the rear at a speed of 50–60 miles per hour. It had passed a colour light signal at caution, two semaphore signals at danger, and had burst through the trailing points of the crossover from the slow lines. The collision completely destroyed the rear three coaches of the local train (where most of the casualties occurred) telescoping them into the length of one coach, and drove the entire train forward 20 yards. The leading two vans and three coaches of the Perth train piled up behind and above the locomotive.The wreckage from the first collision was spread across the adjacent down fast line. A few seconds after the first collision, the northbound express to Liverpool Lime Street passed through the station on this line in the opposite direction at approximately 60 miles per hour. The leading locomotive of this train struck the derailed locomotive of the Perth train and derailed. The two locomotives from the Liverpool train were diverted left, mounting the platform, which they ploughed across diagonally before landing on their side on the adjacent DC electric line, one line of which was short circuited by the wreckage; the other line had its electric current quickly switched off by the signalman, thus preventing any further collisions. The leading seven coaches, plus a kitchen car from the Liverpool train were carried forward by momentum, overriding the existing wreckage and piling up above and around it. Several of these coaches struck the underside of the station footbridge, tearing away a steel girder.Sixteen vehicles, including thirteen coaches, two bogie vans and a kitchen car were destroyed or severely damaged in the collisions. Thirteen of these were compressed into a compact heap of wreckage 45 yards long, 18 yards wide and 18 feet high. The Perth locomotive was completely buried under the pile of wreckage.Casualties
There were 112 fatalities, including the driver and fireman of the Perth express and the driver of the lead engine of the Liverpool express. 102 passengers and staff died at the scene, with a further 10 dying later in hospital from their injuries. Of the 108 passenger fatalities, at least 64 occurred in the local train, 23 in the Perth train, and 7 in the Liverpool train. The remaining 14 were unclear, but some of the fatalities may have been standing on the platform and hit by the derailed locomotives of the Liverpool train. A total of 340 people reported injury: 183 people were given treatment for shock and minor injury at the station and 157 were taken to hospital, of whom 88 were detained.
- At around 8:17 am, on 8 October 1952 the local train had stopped at platform 4 at Harrow and Wealdstone station, approximately seven minutes late because of fog. Carrying about 800 passengers; it was busier than usual because the next Tring -Euston service had been cancelled. As scheduled, it had travelled from Tring on the slow line, switching to the up fast line just before Harrow and Wealdstone to keep the slow lines to the south of the station clear for empty stock movements. At 8:19 am, just as the guard was walking back to his brake van after checking doors on the last two carriages, the Perth express crashed into the rear at a speed of 50–60 miles per hour. It had passed a colour light signal at caution, two semaphore signals at danger, and had burst through the trailing points of the crossover from the slow lines. The collision completely destroyed the rear three coaches of the local train (where most of the casualties occurred) telescoping them into the length of one coach, and drove the entire train forward 20 yards. The leading two vans and three coaches of the Perth train piled up behind and above the locomotive.The wreckage from the first collision was spread across the adjacent down fast line. A few seconds after the first collision, the northbound express to Liverpool Lime Street passed through the station on this line in the opposite direction at approximately 60 miles per hour. The leading locomotive of this train struck the derailed locomotive of the Perth train and derailed. The two locomotives from the Liverpool train were diverted left, mounting the platform, which they ploughed across diagonally before landing on their side on the adjacent DC electric line, one line of which was short circuited by the wreckage; the other line had its electric current quickly switched off by the signalman, thus preventing any further collisions. The leading seven coaches, plus a kitchen car from the Liverpool train were carried forward by momentum, overriding the existing wreckage and piling up above and around it. Several of these coaches struck the underside of the station footbridge, tearing away a steel girder.Sixteen vehicles, including thirteen coaches, two bogie vans and a kitchen car were destroyed or severely damaged in the collisions. Thirteen of these were compressed into a compact heap of wreckage 45 yards long, 18 yards wide and 18 feet high. The Perth locomotive was completely buried under the pile of wreckage.Casualties
-
- In LMS days, down expresses not stopping at Rugby were signalled by special block codes, depending on whether they were taking the Trent Valley or Birmingham routes. The driver would give the appropriate code at Weedon, the bobby there phoned the route to his colleague at Hillmorton box, and from there the train was offered right through to Rugby No 7, where the routes diverged, as 4-4-4 for Trent Valley trains and 4-4-4-2 for Birmingham.
- One afternoon in 1939, soon after the colour lights were brought into use (by which time switch diamonds had been laid in for the down fast Trent Valley/up Birmingham crossing) the down side signalman at No 7 was offered, and accepted, 4-4-4-2. Odd, because he was expecting 4-4-4 for the Mid-day Scot, with the Birmingham following. He set the road and then made enquiries whether the trains were out of course. Nobody knew. Thus, as the train came into view, he studied it closely and recognised a Princess on a long train with roof headboards all the way; undoubtedly the Mid-day.
- Panic! He threw back the signals, and, despite what the rule book might have said about not changing points within the clearing point, started to reset the road in front of the train, approaching to take the 45mph diversion to the Trent Valley. It was quite a road to set, what with switch diamonds and several “trap” routes to avoid potential conflict, and before he had got very far into the operation a glance told him that he could not complete it in time. So he hastily abandoned the move and feverishly reset the road as it had been – just as the Princess thundered past, only then beginning to brake. It stopped ½ a mile towards Birmingham.
Preserved British Steam Locomotives 