Succeeding the Leyland Royal Tiger underfloor-engined heavyweight single-decker bus or single-decker coach chassis which sold more than 6,000 from 1950 to 1956 was a difficult call, but Leyland answered it with the Royal Tiger Worldmaster, it retained a substantial steel ladder-frame chassis dropped in the wheelbase and overhangs and arched over the axles to which operators could fit a body of their choice.

A Leyland O680H horizontal engine (the smaller-volume 0.600H was optional but rarely chosen) was mounted at the middle of the chassis frame, driving back through a pneumocyclic semi-automatic gearbox to an overhead-worm rear axle, steering was via a worm and nut mechanism.

Left-hand drive Worldmasters were either LERT or LCRT, to tabulate the basic range: Operators in every inhabited continent bought Worldmasters, big markets were western and southern Africa, Australia, South and Central America, the Middle East (notably Israel), the Caribbean and Continental Europe, both Eastern and Western bloc.

The arrival of the L1/2 Leyland Leopard in 1959 followed by the PSU3 version in 1961 confined UK-registered Worldmasters to a trickle of undelivered export chassis, one of which (an ERT2/2) went to Happiways of Manchester in 1963, bodied by Duple (Northern) in the former HV Burlingham factory.

Ayats in Spain produced an LERT1 whose frontal aspect resembled the Edsel car,[6] and many other coachbuilders made pan-continental names bodying the Worldmaster, DAB in particular, able to respond in 1959 to a short-notice order from Poland's state tourism authority, became favoured by and eventually taken over by Leyland.

One noteworthy customer of the Israeli-bodied variants (both Ha'argaz and Merkavim) was the ITB of Bucharest, SR Romania, which took delivery of multiple buses in 1968–1969; this was seen symbolical of Romanian defiance against Soviet policies at the time.

From the mid-1970s West Africa was the last stronghold of substantial Worldmaster orders, Lagos Municipality in particular favouring the type, using Marshall and Willowbrook dual-door bodies to an outline resembling British Electric Traction standard Leyland Leopards but with bigger tyres, greater ground clearance and an inherent toughness of character no Leopard ever possessed.

Ellen Smith found its two Worldmaster RT3/2s too good to scrap after a decade of high-mileage use, instead they were fitted with new Plaxton bodies in 1968 and 1970, the latter coach is preserved.

MTT (Metropolitan Transport Trust) in Perth, Western Australia, rebodied their 1957 Worldmaster, fleet number 21, in 1967, the bus stayed in service until 1982.

In the late 1970s and early 1980s Uruguay's capital Montevideo's bus operators CUTCSA (the most frequent Leyland client in Uruguay) and COTSUR rebodied multiple Worldmaster chassis with unsatisfactory results citing it was expensive and produced an mechanically aged product; CUTCSA rebodied the chassis sourced from heavily damaged and/or burned down buses at its own workshops with their in-house designed Banda Oriental (name used by the Spanish Empire for their former Uruguayan territories) family of bodies while COTSIR its units 18 and 95 rebodied by.Carrocerias "La Victoria" (The Victory Bodyworks) in a model of body named "Ñandu Metropolitano" (Metropolitan Rhea) followed years latter by an in-house modification of units 39,68 and 90[citation needed] A 12 ft 6 in (3.81 m) wheelbase version of the Worldmaster with 0.680H engine, five-speed gearbox and two-speed rear-axle with the radiator relocated to the UK nearside just ahead of the rear-axle was sold from 1958 to fire-appliance builders as the Leyland Firemaster, the unique selling-point being that a water pump with power take-off from the transmission could be fitted at the extreme front of the chassis allowing the Firemaster to nose-in to incidents and be ready to deploy water hoses in half the time of conventional front-engined fire engines.