On the gas bus topic, I have no photos of my own, but attached are three by Les Perkins, which appeared in a little book published by the Birmingham Transport Historical Group in the late 70s, entitled 'Memories of Birmingham's Transport'. I remember the scene quite well, as I was given a bicycle for my 10th birthday on 3 July 1943, and used to cycle at lunch times down from Hawthorn Road Juniors to the Finchley Road terminus to watch the antics involved in keeping those buses on the move. I wouldn't have been surprised if my new bike and I had appeared in one of those pics, except that transport enthusiasts don't let people get in the way of their subject, especially in front of the fleet number.
On the subject of the designs published today for a double deck bus to replace the London bendy-buses (which was in our Boris's manifesto before he was elected Mayor of London), I am rather disappointed that so much public money has been spent on paying celebrity designers to faff around on things that wouldn't work, and almost certainly do not conform with modern health and safety requirements.
I'm not saying the Routemaster was not a good bus (not as good as Midland Red's D9, mind you), but I do think for its time the RT was a greater step forward.
So far as Birmingham Corporation is concerned, I would go for the Leyland-bodied TD6cs of 1939. Smooth efficient and workmanlike design, the sort of thing you don't see any more.
Peter