My Moother-in-law owns her house, and the adjoined semi is owned by a buy-to-let landlord. They're ex-council, mid 1960s.
The guttering is the usual setup: a run the full width of the pair, with one house having the front downpipe, one the back- in this case, hers is at the front.
Anyway, the guttering at the back is leaking/overflowing in the area on her property. She's had someone to look at it, and the neigbouring bit is (a) blocked between her house and the downpipe, (b) insecure, and (c) allegedly consists of plastic guttering fitted over the old iron stuff. I can't verify this, however, easily.
My question is this: obviously she should contact the landlord, and ask him to maintain the guttering; but what is the best course of redress, and her rights, if he doesn't? FWIW, she has a good relationship with the tenants.