Included in the motorbus fleet were a small number of petrol-electric vehicles, manufactured by Tilling-Stevens of Maidstone.

The General Manager of the municipal transport section was Charles Owen Silvers, and he was sufficiently impressed by the performance of the vehicles that he pressed for a system where the petrol engines were replaced by overhead wires.

Although the Corporation had no powers to run trolleybuses, the Ministry of Transport allowed the scheme to be implemented, providing a clause to permit such operation was included in their next Parliamentary Bill.

The route was hampered by a low railway bridge, and so six single-deck vehicles were obtained from Tilling-Stevens, which were fitted with Dodson centre-entrance bodies.

The conversion work took place in stages, with the first part from Snow Hill to the Fighting Cocks public house on the borough boundary opening on 26 October 1925.

[6] The last trams ran in August 1928,[5] which allowed the route to Bilston to be opened on 19 November 1928, and this was extended on 28 May 1929 to reach Darlaston.

It was at this point that the system became the largest in the world, with around 25 miles (40 km) of route, and the service being used by 36 million passengers a year.

[6] In 1930 a circular service to Whitmore Reans began operating, which included a branch specifically to serve the Courtauld's textile works.

A new departure was the route from Willenhall to Fighting Cocks, which did not involve the trolleybuses starting at the town centre.

[5] The joint working began on 16 November 1931, after a low bridge on the Willenhall route was modified to allow the running of double-deck vehicles.

Trolleybuses ran to Bushbury Hill from 30 November 1931, and to a number of developing residential areas subsequently.

The Amos Lane and Pear Tree routes opened on 21 March 1932, and on 10 April 1933 a service began serving Brickkiln Street, Jeffcock Road and Bradmore.

The Wednesfield route was extended to Lichfield Road on 10 February 1934, and trolleybuses replaced motor buses on Oxbarn Avenue the following day.

Joyce et al. state that 38 extra vehicles were obtained to meet wartime traffic levels.

[5] The fleet list published in Joyce et al. shows 18 Sunbeams entering service between 1940 and 1942, and 38 Sunbeams with utility bodywork arriving between 1943 and 1946, so the earlier reference to 38 vehicles appears to cover the utility vehicles, some of which did not enter service until the war was over.

In 1961 there were some 150 vehicles operational, but the Transport Committee decided that the trolleybuses should be withdrawn, and the routes were progressively closed.

[9] Next to go was the Fordhouses to Bushbury Hill service, on 26 January 1964, and on 26 October, the route from Willenhall to Bilston and Fighting Cocks ceased to operate.

433, a Sunbeam W4 supplied with BTH electrical equipment and Park Royal utility bodywork in 1946, was one of the batch rebodied in 1958/59 by Roe.

It remained in service until the system closed, and now operates at the Black Country Living Museum in Dudley.

It returned to the system for tours on the final day of operation, and then moved to a Ministry of Defence site, where it was severely vandalised in 1968.