Yes, Anne! 07:21 Nov 6, 2013
PRs used as a plural countable noun here is in fact short for 'PR people' (etc.), and it would mean anyone doing PR for Jermyn St-like businesses — the point being that about the only place one finds the word 'gentleman' used nowadays in EN is in texts about 'Gentleman's tailor' etc.; oh, and on the doors of public toilets! Hence the reference specifically to Jermyn St.
By way of an off-topic anecdote, in the 1930s my Mum worked as a book-keeper for a Jermyn Street tailor; late one evening, most of the staff had gone home, when in walked the King of Norway, asking if a button could be sewn back on his shirt. In the absence of their tailoring staff, they asked my Mum to do it, but she was so nervous, her hands were shaking and she had trouble! | 
peer agreement (net): +4