6203 was built at Crewe Works in July 1935 at a cost of at a total cost of £9,692 for engine and tender being first of the production batch of locomotives. It entered revenue earning service in July 1935 hauling a train from Crewe to Euston. It was initially allocated to Polmadie depot in Glasgow but. was subsequently allocated to Camden depot.
It was named Princess Margaret Rose after the then five-year-old daughter of Albert, Duke of York (later King George VI), Princess Margaret Rose, the younger sister of Queen Elizabeth II.
The locomotive was used to haul the heaviest and fastest LMS passenger trains from London to north and northwest England and to Scotland.
BR motive power depot allocations since 1948.
| Date Arrived | Depot |
| January 1948 | Crewe North |
| February 1948 | Edge Hill |
| September 1951 | Polmadie |
| May 1953 | Edge Hill |
| June 1953 | Crewe North |
| September 1958 | Edge Hill |
| August 1960 | Camden |
| September 1960 | Edge Hill |
| March 1961 | Carnforth |
| July 1961 | Crewe North |
| September 1961 | Carnforth |
| January 1962 | Carlisle Upperby |
| April 1962 | Carlisle Kingmoor |
During its twenty seven years of service to the LMS and British Railways, 46203 covered one and a half million miles and on the 3rd. May 1936 attained the class speed record of 102.5 mph between Tring and Cheddington during a vacuum brake test run between Euston and Crewe.
46203 was the only LMS pacific ever to visit Derby works for major repairs (to overcome loose outside cylinders and replacement of front end frames), this taking place between 10th. December 1951 and 17th. March 1952.
46203 was withdrawn from service at Carlisle Kingmoor in October 1962. The total mileage officially recorded between 1935 and 1961 was 1,494,484 but it is now known that it completed at least an additional 9,000 miles during 1962.
After withdrawal, 46203 was bought by Billy Butlin of Butlins holiday camps. After cosmetic restoration at Crewe, it was moved to Pwllheli in Gwynedd, arriving there in May 1963.
Still under the ownership of the Butlins group, it was moved to The Midland Railway Centre during 1975, arriving at Butterley on the 5th. November, where it remained as a static exhibit until purchased from Butlins in October 1988 for £60,000. 46203 was then quickly restored to full mainline operating standards and returned to service on BR metals in June 1990.
During late 1994, The Princess Royal Class Locomotive Trust was formed, and in early 1995 Princess Margaret Rose was transferred into the ownership of this charitable trust to secure its long term future.
It then operated on the UK mainline rail network for several years, hauling special charter trains.
A major overhaul of the locomotive is now required, and this may take up to 2 years, as the opportunity will be taken to fit an air brake system at the same time.
The major element of the overhaul will consist of boiler work, which entails the removal and renewal of all the boiler tubes – 112 small and 32 flue, followed by a comprehensive examination of the boiler barrel, firebox and water spaces. Of the mechanical items, the inside motion will be taken down and refurbished. Inside cylinder pistons and valves will be removed for examination, and piston valve rings probably renewed. Finally engine and tender will be repainted. Total expenditure for the whole of the work is expected to be in excess of £100,000.
| Home Base | Current Status | Owner |
| Midland Railway – Butterley | On static in the West Shed Museum at Butterley | Princess Royal Class Locomotive Trust |
Preserved British Steam Locomotives 