Around the same time that the Class 142 was developed, another class of Pacer railbus was designed by Kilmarnock-based Hunslet-Barclay. These used a Walter Alexander bus body. They were given the number Class 143 and started being used in 1985. Its two 205 bhp engines gave a total output of and a top speed of . This class of Pacer originally had a capacity of 122 passengers. They were used in the North East before being transferred to Wales and the South West, and were moved over to Valley Lines and Wales & West control during privatisation. They then passed on to Arriva Trains Wales, Wessex Trains, First Great Western and Transport for Wales. The interiors were completely changed in 2000, when the Valley Lines service was introduced, with full back, coach-type seating installed throughout, along with improved fittings. This reduced seating capacity to 106 seats per set.