Up until yesterday I hadn't come across this site before: http://www.fixmystreet.com/
Essentially it allows you to flag an issue with a street, road, building works etc... which is then sent through to the relevant council.
I hit a big pothole about two weeks ago and got two pinchflats from it, so thought this would be a good test. I'm sure the pothole has been there for longer, but i have only noticed it for the last two weeks.
Anyway I reported the hole yesterday morning, had an email from TFL around 3pm saying thanks for my enquiry. Then rode past around 8pm and there was a team filling the hole in! Top marks to FMS and TFL!