The service on Bank Holidays was so popular that demand outstripped available DMUs, and a relief train of four coaches pulled by No. 3749 was laid on. Two more 5700s were used over the Spring Bank Holiday that year, but from then BR Standard Class 4 2-6-4T locomotives usually handled the relief services. In 1965 5700s were used for the last time on Whit Monday and August Bank Holiday relief services. The 5700s were the last steam locomotives used on GWR/Western region. The last working locomotives were allocated to Croes Newydd, and were working goods trains and shunting until November 1966. By the end of the steam era the record keeping of allocations and working of local steam locomotives was rather lax, and it was not unknown for locomotives to be used after being officially withdrawn. For many years Nos. 4646, 4696, and 9774 were thought to be the last ex-GWR locomotives to work on British Rail, but No. 9641 was also still in steam at Croes Newydd at the same time. There were numerous other classes of pannier tanks built by the GWR. The majority belonged to two "families" of "large" and "small" designs. Others included absorbed stock, more specialised types and conversions of tender locos. The two main groups were:-   For example, within the "small" group, the GWR 5400 Class locomotives were derived from the William Dean -designed GWR 2021 Class (an enlargement of the 850 Class), with larger wheels for higher top speed and fitted with autotrain apparatus ('auto-fitted') for push-pull passenger work. The GWR 6400 Class were similar to the 5400 Class, also being auto-fitted, but having the same size wheels as the 5700. The GWR 7400 Class were very similar to the 6400 Class, but were not auto-fitted and had a higher boiler pressure. Within the "large" group, the GWR 9400 Class was the post-war updated design of the 8750 variant of the 57xx: heavier and longer, but nominally no more powerful, using the same taper boiler as the GWR 2251 Class. For a list of classes, see GWR 0-6-0PT. After the 1955 Modernisation Plan, the reduction in branch line work and the introduction of diesel shunters, the Western Region embarked on dieselisation programme which, along with a reduction in branch line work, reduced the demand for the services of the 5700s.