Styling was carried out by the Italian vehicle stylist Giovanni Michelotti, previously commissioned by both Triumph (Herald, TR4, GT6, 2000/2500, 1300, Dolomite and Stag) and Scammell lorries (Routeman GRP cab).

The third length was 10.9 metres (35 ft 9 in), specially produced for Australian operators due to stringent axle weight limits.

The prototype of this latter version was sold to a Scottish operator, Rennies of Dunfermline, and was fitted out to dual purpose coaching specification for use on express services.

Leyland engineers found that during the development of the National, body repairs could be completed at least a tenth of the time quicker than on buses with conventional welded panels.

This just predated the decision by the National Bus Company to standardise on two colours: poppy red and leaf green.

[3] In 1978, Leyland brought out a simplified model, the Series B, intended to replace the Bristol LH which had been in production since 1967 and was a type popular in NBC companies for rural routes.

It was available at only 10.3 metres (34 ft) in length and had a revised interior that featured minimal lighting and removed the rear roof-mounted heating unit in previous models.

This engine did not prove popular with all operators, being prone to poor fuel consumption and heavy smoke production if not maintained to high standards.

[1]: 380 Some operators experimented with a different engine and found they could avoid the 510, which had the reputation of being a high maintenance unit and hard to work on.

In years to come, with all of the pressures created by deregulation, operators began refurbishing their Nationals for extended service, often retrofitting DAF or Volvo engines.

[16] The export version of the Leyland National was constructed in the standard way, although some were what might be called a hybrid, consisting of longer windows up to the rear axle and shorter ones after.

[8]: 456 Nederlandse Spoorwegen in the Netherlands purchased 25 on behalf of their bus subsidiaries NZH, Westnederland, Centraal Nederland and Zuidooster.

[8]: 466 As a result of legislation preventing the use of step-entrance buses on normal public bus routes, no Nationals remain in service.

[29][30] In the 1980s, Leyland National bus components were also used to build a family of railbuses and multiple units for British Rail: Pacers Super Sprinters Despite the best intentions, the front end of the Leyland National was not considered substantial enough to allow for a standard bus front end to be used on train carriages.