They were preceded by C-class buses for Córas Iompair Éireann which were to the same length as the PSU4 but coded PSU3.4R From 1968 Leyland introduced the A suffix across all existing passenger models, this denoted the rationalised Pnuemocyclic gearbox when fitted: this replaced various AEC and Leyland epicyclic transmissions and included a ten-speed splitter version offered in the Super Beaver articulated lorry this was built in a new extension to the Farington works.

[11] Scottish Bus Group continued to take the manual-gearbox Leopard with O.600 engine until that was discontinued in 1972/3, the O.680 powered Leopards with the Leyland part-synchromesh gearbox were still coded PSU3.3R [12] Late in 1974 spring-operated parking brakes, automatic brake adjusters, a water-cooled air compressor and a revised engine mounting resulted in a change to PSU3C, PSU4C and PSU5A.

[15] In 1979 the twentieth year of Leopard production, the tyre equipment and coolant warning system were revised, the wide ratio Pneumocyclic with direct air operation again became standard and the ZF S6-80 six-speed synchromesh became a general sale option on coach chassis designated by .5 these were the PSU4F, PSU3F and PSU5D[16] In 1982 with the TL11-powered Tiger already launched, the PSU4G, 3G and 5E had a rationalised O.680 which shared TL11 components.

For buses and dual-purpose vehicles, a BET standard design of bodywork was produced, primarily by Marshall and Willowbrook but also to a lesser extent by Weymann and Metro-Cammell.

Another major English customer for the Leyland Leopard was Barton Transport of Chilwell near Nottingham, which built up a fleet of 200 with Plaxton Elite and Supreme coach bodywork.

During the 30 years of The Troubles in Northern Ireland, a total of 228 Leopards were stolen from their depots and maliciously destroyed in public streets.

[21] The Public Transport Commission purchased 745 for use in Sydney and Newcastle between 1967 and 1976 giving it the world's largest Leopard fleet.

[27] In 1980, Auckland tour operator Bonnici Coachlines purchased ten 12.5 metre three-axle Leopard coaches.

Bodied by Walter Alexander Coachbuilders and registered as SBS6791L, it was an early example of the mid-engine bus in Singapore, preceding even the much larger orders of the Volvo B10M in the 1990s.

Despite favourable reviews from SBS, no further units were purchased and SBS6791L was returned to the UK and sold to Woods of Mirfield, West Yorkshire.