I came across this interesting article,
http://www.english4italy.com/2013/10/20/robert-winders-bloody-foreigners-the-story-of-immigration-to-britain-the-italian-link/Seems many of them in London were Italian boys who lived in appalling conditions.
Interesting subject, there is an association of street organists in the uk who do fairs and such.
I've only seen them in fairs. There was one in our local annual fair not so long back (wasn't the barrel type, it was the big steam type, beautiful thing. It was run by an old bloke, who also had some very beat up puppets that looked better suited to a horror movie.
Is he in any of the censuses? Is he a street organist in them too?
Have you searched the online newspapers with his name? Being a busker, you may get lucky that he has fallen short of the law a few times (I have a peddler and he makes the papers r on a few occasions for peddling without a license )
There is a company that still make them in them in the uk if you've got a few grand to spare
http://www.deanorganbuilders.co.uk/index.htmKind regards

(Excuse any typos , I am using my phone)