Carole, that is absolutely fantastic. I'd never thought of Flickr as a source of info.
What makes it even better is that I know Anthony and Jonathan Alsop, who responded to the publication of the photo - both were very useful amateur boxers and now coach the sport. It just never occurred to me that they might be related - the difference in spelling presumably got in the way. I note that John signed his picture 'Alsop' rather than 'Allsopp', so that must have been the correct way.
I'll get in touch with Anthony straightaway.
I was a bit dubious about inquiring on this forum, as I didn't really think it was going to get me anything I could be certain was the right man. Not for the first time, I underestimated the brilliance of RC members

Gareth