 The first models of 1979 was based on the Leyland National, but was powered by a Saurer 240 bhp underfloor engine and Allison fully automatic transmission instead of the Leyland components.Other parts like the axles and the steering mechanism, were also from Leyland.Four of these buses saw extended trials in the United Kingdom with the South Yorkshire Passenger Transport Executive, (SYPTE) and were demonstrated with other UK operators, with seven purchased by British Airways.