'Railless' No 11, OK 4833, was new in 1922 and ran until February 1932. They were the first covered-top trolleybuses in the country, and 'Railless' referred not only to their chassis maker's name but also to the fact that they were considered as trams without rails rather than buses. Some cities called them 'Trackless trams'.
Their bodywork was by Charles Roe of Leeds, electrical equipment (including tram-type hand controller) by Dick, Kerr & co., and they were powered by two 42 HP motors, one driving each rear wheel. They were 24'6" long, 7'6" wide (Birmingham's trams were only 6' wide and ran on narrow gauge [3'6"] tracks), 16'3" high and each one (there were 12 of them) cost £3000. Not cheap in those days.
The photograph was taken during a demonstration run, and was specially posed by the road works to show how, unlike trams, trolleybuses could negotiate around obstacles blocking their path.
Here's a view of similar bus no 6 in Washwood Heath depot yard.
