I disagree that your vote was wasted. It contributed to the Lib Dems leapfrogging the Torries, pusing them into third place (The Tories had a MP in Walthamstow until 1992), provide the Lib Dems with teh second largest swing from Labour in London (over 12%) and thirdly puts Walthamstow amongst the top 100 most winable seats.

Next year you will have an opportunity to vote for the Lib Dems locally. Locally the Lib Dems are already in second place (Labour 17 seats, Lib Dems 7 and Tories 0) and are set to make many more gains.