80104 was built at Brighton in March 1955 at a cost of £18,206. 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 into storage at Old Oak Common depot and subsequently at Croes Newydd and later on to Machynlleth. Whilst at Machynlleth it passed to London Midland Region ownership when a number of depots were transferred to the London Midland Region in September 1963.
The locomotive’s first overhaul was at Stratford in September 1956, followed by a heavy overhaul at Darlington works during May 1958. After the transfer of its maintenance to Crewe in June 1962, 80104 received a heavy overhaul there in October 1962 and a heavy general repair there in December 1962.
Motive power depot allocations.
| Date Arrived | Depot |
| March 1955 | Plaistow |
| November 1959 | Tilbury |
| July1962 | Old Oak Common (stored) |
| November 1962 | Croes Newydd |
| March 1963 | Machynlleth |
In June 1962 the locomotive was placed in store following the electrification of the LT&S routes. It was transferred to the Western Region in July 1962 and placed in store at Old Oak Common.
80104 was withdrawn from service in July 1965 and sold to Woodham Brothers for scrap. It arrived in the scrapyard at Barry in January 1966 and remained there until September 1984.
80104 was bought by the Southern Steam Trust who already owned classmate 80078.
It was cosmetically restored and placed on display in the head shunt at Swanage where it remained for a number of years. The locomotive was sold to a group of supporters in January 1988 when it became obvious that restoration would not be possible in the near future. It was then sold to the new owners who called themselves 80104 Limited.
The locomotive was moved to the former Swindon Works Weighbridge for restoration in November 1989 where it joined 34072 257 Squadron which was undergoing restoration. Work commenced alongside 257 Squadron and the locomotive was dismantled during the summer and autumn of 1990.
In 1991 80104 was moved to the Avon Valley Railway following eviction from Swindon.
In November 1994 ownership of the engine was transferred to Southern Locomotives Limited.
As a result of both the opening of Herston works and the negotiation of a financial package to speed its rebuilding, 80104 returned to Swanage during August and October 1995. Various major milestones were passed during the following year including re-wheeling. The side-tanks and bunker were rebuilt at Bitton and the boiler was refurbished by a specialist firm. By Autumn 1996 the locomotive was beginning to take shape and in March 1997 the boiler passed its hydraulic test and then its steam test. Both of these tests required the boiler to be out of the frames.
Once the boiler (The repaired boiler from 80078) had been fitted to the frames the final assembly of the cab and countless other fittings took place and the locomotive left Herston Works on a low-loader for the road journey to Norden in April 1997.
The locomotive was drawn from the low-loader at Norden by Midland Railway class 1F 41708 before being towed to Swanage
It was not until 30th April that the Insurance Company’s boiler inspector gave his approval and the locomotive moved under its own power for the first time since July 1965. That evening the locomotive completed about 24 miles with no problems being encountered.
The locomotive had been booked for the 30th Anniversary re-run of the Dorset Coast Express in May and a final flurry of activity saw the engine completed in plain black livery bearing the number 80011. The locomotive made a few test trips up and down the line and then made its first public appearance with 257 Squadron which was disguised as 34023 Blackmore Vale for the re-enactment of the Dorset Coast Express.
The locomotive was then given a proper paint and lining job and joined the operational fleet of the Swanage Railway.
Following several years of successful operation, during which 80104 journeyed to the Avon Valley, Mid-Hants and Great Central Railway for a short periosd, it was withdrawn from traffic in January 2005.
As the Herston team were heavily occupied with the restoration of Manston, and the contracted job of completing GWR 0-6-2T 6695 whose owners had found it impossible to finish themselves, it was decided to send the locomotive to outside contractors in Wigan for much of the repair work that needed to be accomplished.
Unfortunately, during 2005, the contractors were given notice to vacate their workshops and it thoroughly disrupted their work schedule. 80104 was transferred to their new facility at Embsay but progress was slow, so it was decided to bring it back to the South to an alternative contractor in Portland, Dorset. This was close enough for local staff to assist with the work and 80104 was brought back in to traffic during 2006.
80104 was taken out of service in May 2016 for overhaul but is expected to return to service during 2017.
In July 2017 80104 was in a head on collision with 34070 during shunting operations between the engine shed and signal box at Swanage. After having a buffer replaced the locomotive was expected to be operational again shortly afterwards but it then failed with six blown superheater elements. It was anticipated that by October 2017 the locomotive would be operational again.
The boiler certificate expired in May 2021. There are no immediate plans to overhaul the locomotive.
In June 2021 it was reported that a shareholder of the owners had offered to provide an interest free loan to cover to cover three quarters of the cost of overhauling the locomotive. Tyseley have provided a quote for the work which is hoped will be completed by the start of 2023.
The locomotive was moved to Tyseley in October 2021 for the contracted overhaul to commence.
In November 2022 it was disclosed that many of the firebox tubeplate holes had expanded to an unacceptable size but it was believed that they could be repaired.
| Home Base | Current Status | Owner |
| Swanage Railway | Under overhaul | Southern Locomotive Ltd |
Preserved British Steam Locomotives 