I am also fascinated by the history of victorian london, I like Sherlock Holmes and books like that, so I often wonder what it was like way back then. I will give you that, nothing like that is built now, the victorians were way ahead of their time, amazing brickwork that has stood the test of time. I agree thinking about where to change out of it, is a bit weird, should drainers bring a decon shower and towels and a full change of clothes with them,,,,...put them all in a bin liner and wash them all in bleach seperate from your wife or kids washing if you a married or family man, if you are a single bloke, just tip the lot into the machine or down the laundrette, even in a sewer it is diluted with rain water and run off from other water (streams and the like).