That's the one, well found.
Just realised I may have thrown some people off the scent earlier as I said I didn't think it was Austin-based (as all his other cars of the period were Ford-based) and I thought this one had the Ford 10hp engine in, at least. Sorry if I accidentally mislead anyone!
I purchased this photograph earlier in the year. As far as I know it's not been published before, but its obviously from the same set of images that are used, poorly, in the book. Tony Russell had never seen it, either