Great Western Railway
Great Western Railway (GWR) is a Train Operating Company based in Swindon which operates services from London Paddington to the West Country and South Wales, including Bristol, Cardiff, Exeter, Gatwick Airport and Plymouth.

Rolling Stock
Great Western Railway has a large fleet of trains including 150, 158, 165, 166, 175, 230, 255, 387, 800 & 802.
The Class 255 Castle Sets are used on the Penzance to Plymouth/Exeter services, with the class 175 in the process of replacing them.
Regions
Great Western Railway operates three separate regions which are London Thames Valley, Intercity and Western.
London Thames Valley (LTV) is the London Paddington to Oxford, Didcot and Newbury services, the North Downs Line, the Basingstoke, Henley-on-Thames, Marlow, Windsor & Eton Central and Greenford Branches.
Intercity is the majority of the services from London Paddington using IET's.