80078 was built at Brighton at a cost of £17,364 and entered service in February 1954. It was based on the Eastern Region working on the London, Tilbury and Southend Line (LT&S) working commuter services out of London until that route was electrified in 1962.
In July 1962 it came under Western Region ownership when it moved to Shresbury and later on to Croes Newydd at Wrexham. Whilst at Croes Newydd it passed to London Midland Region ownership when Croes Newydd (along with Shrewsbury) were transferred to the London Midland Region in September 1963.
Motive power depot allocations.
| Date Arrived | Depot |
| February 1954 | Plaistow |
| November 1956 | Tilbury |
| June 1962 | Stratford |
| July 1962 | Shrewsbury |
| February 1963 | Croes Newydd |
Maintenance records show that 80078 received an intermediate repair at Stratford works during October 1956, followed by a heavy overhaul at Darlington works in December 1960. Its maintenance was taken over by Crewe works in June 1962 and it then received a heavy intermediate overhaul in November 1962 (probably at Crewe).
The locomotive was placed in store in March 1965 before being withdrawn from service in July of that year. After withdrawal 80078 languished in various scrap lines until it arrived at Barry Scrapyard, in June 1966. It remained in Woodham Brothers scrapyard until September 1976.
It was purchased by the embryonic Southern Steam Trust and its move away from Barry and after an eventful journey, including a broken propshaft on the tractor unit, the locomotive arrived at Swanage on 23rd September. Due to some local difficulties, the restoration wasn’t started until 1978, but it was then soon stripped and work begun in earnest. After slow but steady progress during the 1980s, following financial difficulties at Swanage, 80078 was sold to a group known as PROJECT 78 in September 1991.
The new owners continued the restoration work, including the dispatch of the engine’s boiler to R K Pridham Engineering, in Devon, for its repair. Another major landmark occurred in October 1994, when 80078 was the first locomotive to take up residence in the Swanage Railway’s new engineering works at Herston. However, in order to inject new life into the project, the owners decided that an amalgamation with Southern Locomotives Limited would be a good idea and the transfer of ownership was completed in November 1995.
Following completion of work on another Standard class 4MT tank (80104) in April 1997 the team at Swanage was able to devote their full attention to 80078 and the restoration proceeded rapidly.
Following hydraulic and steam tests the boiler was fitted to the frames in September 1999.
On the 1st October 1999 80078 was transported on a low loader the short distance from Heston Works to Norden where it was unloaded onto the Swanage Railway.
80078 had its first steaming on the Swanage Railway a few days later. It operated on the Swanage Railway until its boiler certificate expired in 2010.
In 2012 Southern Locomotives Limited (SLL) sold 80078 to a private buyer who removed the locomotive from the Swanage Railway for overhaul. At the time of the sale SLL had spent £773,000 on the restoration of West Country pacific Sir Keith Park and had little cash reserves for further work on their locomotives.
80078 is at Mangapps Railway Museum at Burnham-on-Crouch in Essex where the owner progressed the overhaul of the locomotive which returned to steam in May 2017 but was taken out of service shortly afterwards. This was because a split left hand cylinder casting which had occurred prior to the engines arrival at the at Mangapps Railway was discovered.
It was back in traffic around Easter 2018.
80078 is nominally based at the Mangapps Railway Museum it is regularly on hire to other heritage railways.
The locomotive hauled some test trains on the Mid Norfolk Railway in November 2020 and will be based there in 2021.
In November 2021 it was reported that the locomotive had been moved to the Swanage Railway where it operated over the Christmas period before undergoing winter maintenance. It returned to the Mid Norfolk Railway in June 2022.
| Home Base | Current Status | Owner |
| Mid Norfolk Railway | Operational | Stewart Robinson |
Preserved British Steam Locomotives 