The London Socialist Alliance (LSA) was an alliance of far-left socialist groups and individuals in London. It stood candidates in the 2000 elections for the London Assembly but supported Ken Livingstone in the mayoral elections held at the same time. It became part of the Socialist Alliance after the elections.

At the assembly elections it polled about 27,000 votes from a total of 2,400,000, and got 1.6% of the vote.

External links