A large number of skip wagons of both side and end tip versions and from many sources were used on the construction of the Deviation but since the completion most have now left the railway. A few may survive in sidings here and there but they have never been numbered in the main wagon series.
During the deviation construction skips were always in short supply. One day someone who headed a large construction company (don't know who) visited the deviation, was told of the shortage and said he could help. A little while later several brand new skips arrived. The lorry driver delivering them said he could not understand why the FR had got them as the company from which they came needed them. They proved to be of little or no use as they could not be tipped without some equipment which the FR did not have.
There is also a series of relatively modern Hudson side tipping wagons numbered 420 - 437 acquired from the CEGB Dinorwic Power Station construction job. These are shown in this picture.