for the two built by the Gloucester Railway Carriage and Wagon Company), resulting in a lower passenger per ton-of-train figure and disdain from BR's operating departments. Further orders to these designs were not forthcoming. Fibreglass bodied vehicles In 1962, Eastleigh Works constructed a single fibreglass bodied Mark 1. The vehicle, numbered S1000S, was mounted on the underframe of Mark 1 Tourist Second Open S4378, which was written off as a result of the Lewisham rail crash in 1957. Only the one example was built due to the cost, making this the only fibreglass-bodied passenger carriage built by British Railways. S1000S was used on the Hayling Island Branch Line until closure in 1963. After use as a generator van at Lancing Carriage Works, it re-entered capital stock. Its final duties were on commuter trains between and . After withdrawal, it was stored at . It was purchased in 1973 by the East Somerset Railway. In 2010, the carriage was restored, and is in service on the East Somerset Railway. Repainted into maroon when work carried out in 2016. A single van, no. E85000, also had fibreglass body panels. This was converted from a normal passenger carriage (Mark 1 Corridor Composite no. Sc15170) at Derby Carriage & Wagon Works in 1970 to carry parcels conveyed in BRUTE trolleys; it was used until 1982. It weighed , even though it was longer than a normal parcels van weighing . XP64 Near the end of the production of hauled Mark 1 stock came a series of eight experimental carriages known as the XP64 set. Three Corridor Firsts, two Corridor Seconds, and three Tourist Second Opens were built by Derby Carriage & Wagon Works in 1964. Externally they resembled Mark 1 stock with the addition of a cosmetic cover over the solebars of the standard Mark 1 underframes, but inside they included many new features, including pressure ventilation, new seating designs and wider bi-fold doors. Many of these features were later incorporated in the Mark 2 stock produced from 1964. Safety The British Rail Mark 1 was considerably stronger than most pre-nationalisation designs, and it was noticed as early as 1952 that the examples involved in the Harrow and Wealdstone rail crash had withstood the impacts better than the older coaches around them. The improvement in safety the Mark 1 thus represented was praised by the Chief Inspecting Officer of Railways, Lt Col I.K.A. McNaughton