Oh wow! Thank you so much for all your input. I haven't had time to take in all your suggestions yet, just logged in to see your replies, but I really am most grateful, not to mention gratified that others like it. It is a great, dynamic action shot.
As to the find - it was in a junk shop in Mysore, India of all places. The shopkeeper knew nothing about it other than that he had bought it with a job lot of furniture in Kolkata. Oh to know the original story behind how it came to be in Kolkata. I did my best to bargain but I know I paid too much for it as I think the shopkeeper could tell at once that I had to have it. It was quite large on its mounting board, couldn't fit in my suitcase, and I wasn't about to risk putting it in the hold on its own so I had some difficulty getting it through security and keeping it by my knees on the plane home. It survived though and is now being looked at by a photograph restorer to see if it can be moved from the badly water damaged mount and have the water damaged spots you can see removed. I don't think the hot and humid Kolkata climate did it much good. I will keep you posted on how I get on.
Once again thank you all for your suggestions and I will be doing some research now. And I look forward to future discussions.