In 1936, Belfast Corporation's tramway committee recommended that an experimental trolleybus service be inaugurated after inspecting the Birmingham, Bournemouth, London, Nottingham, Portsmouth and Wolverhampton systems.

[1][2] Seven pairs of chassis from AEC, Crossley, Daimler, Guy, Karrier, Leyland and Sunbeam were acquired.

These were fitted with six types of electric motor with coachwork by five different builders, and were supplied on the proviso that should the trial be a success, Belfast Corporation would purchase them, and should it fail they would be returned.

[5][6][7] Judged a success, Belfast Corporation decided to replace the entire tramway network.

[3][8] On 13 February 1941 operations began in East Belfast when the Cregagh route commenced from the new Haymarket depot.