 Owned by Network Rail under depot code PM, it is leased to train operator Great Western Railway, and has been used since their introduction for the maintenance of InterCity 125 trains operating between London Paddington, Bristol and South Wales.Both Class 43 power cars and Mark 3 coaching stock are serviced here.Following the merger of First Great Western (FGW) and Wessex Trains operations into one new franchise in 2006, St Philip's Marsh took over the maintenance of FGW's fleet of diesel multiple units, previously maintained at Cardiff Canton TMD by Arriva Trains Wales.