So Ben Aaronovitch mentions the Happy Beaver (ie Felix Castor) novels as works that did not, in fact, influence Rivers of London. Hm, said I, exorcist in London Town, sounds good. Biked to the irritating Sanderson library down Bathurst (irritating because it sits on a very large corner lot and its front entrance is both cunningly hidden and quite unmarked, so one tramps a fair ways in blistering sun trying to find it) and got vol 3, the only thing available at any nearby library. Read some in UofT's Starbux, then went to Bakka and got vol 1. Not that it's as riveting as Rivers or Angels at first glance, but it seems to be set in the same universe more or less and I think will repay investigation.
Then, because I am nothing if not perverse, went on reading The Paths of the Dead. Heat should break some time tomorrow and I too shall break out of the paths of least resistance reading.