The Falkirk based Alexander factory thus meant that the Alexander bodied Ailsa B55s were entirely built in Scotland, a significant factor in securing Scottish orders (notably from the Scottish Bus Group, Strathclyde Passenger Transport Executive and Tayside Regional Council) especially given the ease in securing locally sourced spare parts and repairs.

[4][5] In 1977, an improved Mark II version appeared, with two transmission options offered, a Self-Changing Gears pneumocyclic unit and a Voith D851 with retarder.

By far the most enthusiastic supporter of the Ailsa was Tayside Regional Council who bought 161 examples for use on their Dundee city services between 1976 and 1984, with four different body types, Alexander AV and RV, Northern Counties and East Lancs.

The B55 was popular with the passenger transport executives, with significant purchases made by West Midlands and South Yorkshire and to a lesser degree Merseyside and Tyne & Wear.

The programme was intended to evaluate alternative vehicle types for future fleet replacement in London, which, at that time, was purchasing Leyland Titans and MCW Metrobuses.

This vehicle maintained the usual front entrance door, but had an additional exit behind the rear axle and a second staircase adjacent.

The vehicle remained unique, although London Buses rebuilt the rear, removing the doors, but leaving the staircase in place.

[17] No further orders for new B55s were placed by London Transport, but numerous second-hand examples were purchased from the South Yorkshire and West Midlands PTEs in the late 1980s.

[25] Of the remainder, 64 Ailsas received unusual Van Hool McArdle bodies built in Dublin - 62 buses for the South Yorkshire PTE and two for A1 Service, Ayrshire.

The other, A1 Service PSJ 824R now resides at the Glasgow Vintage Vehicle Trust, previously being based in Sheffield.