The footnote I linked contains several references and full study texts. The short version is that homeless panhandlers are definitely a phenomenon, but the overlap between the two populations is often significantly smaller than might be naively assumed.
Please accept my apologies, I believe I've been unclear. Footnote 26 contains links to several papers that I believe include the salient data. A brief reading of one shows contents such as:
> Begging provided the main source of
finance for this group of people with which
to purchase drugs. It was not uncommon
for them to earn £50 (Approximately $74
US) during a good day. Homelessness was
an issue for around 30 percent of the beg-
gars within the City Centre who were actu-
ally sleeping in the bus station or car park-
ing areas.
Most of the remainder were
technically NFA though, living in squats
on the outskirts of the City Centre or tem-
porarily with "friends," but likely to spend
some time sleeping rough occasionally.
One was living in a hostel and one had a
permanent address.
Maybe I missed it. Could you elaborate?