Originally Posted by
chevvron
But there was a railway line there; single tracked splitting from the main Paddington - Slough line at Yiewsley. What it was used for I don't know but the tracks south of the old Bath Road (no longer the A4 as this designation was transferred to the Colnbrook bypass) were still down up until the '80s at least so probably just used for goods trains;
Line runs right under the M4/M25 junction from the GWR main line, and is still in use for the two concrete/aggregate works located in Thornley and Colnbrook. It was also heavily used for bring in materials and equipment to the purpose built logistics centre set up for building Terminal 5.