When I saw the illo, I gave a start. Until recently I lived in Buxton, Derbyshire a well preserved Edwardian town high in the hills, and there is a street corner to which this illo is identical! Buxton is a spa town and in Beaman's day Buxton was a fashionable destination and people would regularly come up from London to take the waters. I've tried to track down whether he might have gone there but with no success. Of course there might have been a hundred street corners like this in any given town or city at the time - but it was spooky to see it in a horror book!
In the process of looking him up I came across an article that claimed he was given the memoirs of Jack the Ripper! Brrr!
http://news.bbc.co.uk/1/hi/england/somerset/8327573.stm