Growing populations in towns and cities meant larger capacity buses were a necessity, leading Guy to develop a 6-wheeled version of their dropped-frame chassis, which allowed for the introduction of the first 6-wheeled double decker buses and 6-wheeled trolleybuses in 1926. Owen Silvers, the general manager of Wolverhampton Corporation, had pushed Guys to develop the 3-axle bus, and took delivery of the first production vehicle. He then convinced Guys to work with W. A. Stevens, who had developed the Tilling-Stevens petrol-electric bus, of which Wolverhampton had several, and Rees Roturbo Co Ltd, who were also based in Wolverhampton, on the design of a trolleybus. Guys modified their 3-axle chassis, fitting a single Rees-Stevens electric motor at the front of the chassis. Rees Roturbo produced the regenerative control system. The first BTX vehicle, with an open rear staircase, was tested on the Wolverhampton system in December 1926, and Silvers placed an order for a further 58, with enclosed staircases. The Hastings Tramway Co ordered 50 single-deck BTX trolleybuses and eight open-top double-deck versions, while Rotherham ordered five. Guy double decker buses and trolleybuses would prove popular, with a fleet of double deckers sold to the London Public Omnibus Company and exports supplied all around the world. Exports served as a major source of income for Guy with sales to South Africa, Pakistan, India and the Netherlands, their armoured vehicles proving particularly popular for covering difficult terrain, with 100 supplied to the Indian government in 1928.