Belatedly, I would suggest that that first picture was taken in Great Lister Street, while the old tram tracks were being taken up, but before the public service was started. The twelve new trolleybuses were ordered in September 1921, but there was a long hiatus until they entered service on 27 November 1922. The trams were cut back to Nechells Green on 14 August 1922, and the remaining part finished on 26 November, the day before the trolleybuses started. Looking at the picture you can see that although the trolleybus was not in public service, and I would guess that it was a demonstration trip for members of the Tramways (not yet Transport) Committee.
Peter