Thanks for that interesting picture, rocketron. Do you have any idea of the location? It should be possible to pin it down because of the fairly distinctive building, top right.
Also, anything on the date? In the absence of that information, one can see that the group, possibly the best part of an entire battalion, is almost certainly about to set out on a formal parade through the surrounding streets. It even includes a band which may consist of regular Army personnel. Such parades often took place on the May anniversary of the founding of the Home Guard which was celebrated each year with some pomp and ceremony, partly as a public relations exercise. Despite that, however, and despite the fact that the men are not wearing greatcoats, it looks to me as though this was not a summer image. What vegetation there is in the background looks bare and also the small group of civilians to the right (being chatted to by another Home Guard) look as though they may be wearing overcoats.
It is worth noting that in the foreground almost all of the officers are wearing Great War service ribbons. In addition the commanding officer has the insignia of an RFC/RAF observer. This might have helped identify the group but unfortunately at least three of the 30+ Birmingham Home Guard battalions were commanded by ex-RAF personnel. (These battalions were based in King's Norton and Acocks Green and the third was a Birmingham City Transport Battalion and so none of them really fits, I assume).
If you have any further information it would be very interesting to hear it.
Chris