I'm writing something set in Tottenham around 1900, when there is a Jewish hospital in South London, but no synagogue.
(If you decide to go searching for me, be warned there are a lot of *very* unpleasant comments to be found.)
edit: Thanks! I have the information I need. My protagonists become friends with some Jewish lads from Bethnal Green and I suddenly realised that a lot of my dialogue on both sides would be all wrong if the areal was heavily Jewish by then.