The Great Western and Great Central Joint Railway was a railway built and operated jointly by the Great Western Railway (GWR) and Great Central Railway (GCR) between Northolt (in north west London) and Ashendon Junction (west of Aylesbury). It was laid out as a trunk route with gentle curves and gradients and spacious track layouts. The two companies each needed approach railways at both ends of the line to connect their respective systems, and these were built as part of a single project.