3650 was built at Swindon in December 1939 at a cost of £2,844 and finished in plain green livery with tank side GWR roundles.
BR motive power depot allocations since 1948.
| Date Arrived | Depot |
| January 1948 | Tyseley |
| October 1953 | Bristol Bath Road |
| December 1953 | Radyr |
| January 1954 | Cardiff East Dock |
| October 1955 | Abercynon |
| May 1958 | St Philips Marsh |
| October 1961 | Neath |
Following withdrawal in September 1963, having completed 493,100 miles whilst in service, 3650 was disposed of to Stephenson Clarke P.D. Fuels Ltd and following removal of the vacuum brake pipes and steam heat it moved to Gwaun-cae-Gurwen in South Wales, where it was painted blue with red lettering along the tanks and used to move spoil slag heaps. It continued working until fire box bulges, a thin front tube and worn tyres, amongst other things, caused it to be stopped. From the subsequent evidence found during restoration very little maintenance work had been carried out on 3650.
3650 was initially allocated to Tyseley but in 1953 moved to Bristol Bath Road and then Radyr. In the following year it was transferred to Cardiff East Dock where it spent a year before moving on to Abereynon. In 1958 3650 moved to Bristol St Phillips Marsh where it spent three years before moving on once again but this time to Neath in 1961. It was condemned in 1963.
It was subsequently purchased by a GWR member in 1969 and moved to Bulmers at Hereford, where some restoration was done. However, heavy repairs were required, and in 1969 ownership was transferred to one of the Didcot volunteers who moved it to Didcot in 1970.
Didcot already had a 5700 class pannier (tank 3738) which was acquired from Barry scrap yard in 1974. 3738 was in better condition than 3650 so it was but lacked the non ferrous pipe work and fittings which had been removed whilst at Barry. It was decided to use 3650 as a source of spares for 3738 being a far easier restoration project. As a result 3738 was working again in two years.
In 1984 further dismantling of 3650 commenced, firstly the tanks were removed followed by the cladding later that year. The boiler was removed two years later followed after another year by the wheels. In 1987 3650 moved into the newly erected workshop at Didcot and restoration work commenced.
After some 20 years of restoration effort the boiler inspection was satisfactorily completed in July 2008 and the locomotive became available for traffic. Initially the locomotive was turned out in “industrial” Stephenson Clarke blue livery, but once run in it was painted into its original Great Western “shirt button” badge livery. It became available for traffic in its new livery in April 2009.
The locomotive was taken out of service in 2016.
The overhaul of 3650 started in July 2018 with the aim of having it back in service in 2021.
| Home Base | Current Status | Owner |
| Didcot Railway Centre | Under overhaul | Group of Great Western Society members |
Preserved British Steam Locomotives 