(Corrects margin of loss to 422 votes not seats)
LEEDS, England, May 8 (Reuters) - The Labour politician who had vied to become Britain's next finance minister has lost his seat in parliament, election officials said on Friday, in one of the most high-profile losses for the opposition at Thursday's national election.
Ed Balls, a Labour member of parliament since 2005 and a long-time ally of former Prime Minister Gordon Brown, lost his seat on the outskirts of the northern English city of Leeds to a Conservative challenger by a margin of just 422 votes.
Exit polls published late on Thursday suggested Labour will win 239 seats in the 650-member parliament, down from 258 in 2010 and its lowest total since 1987. The ruling Conservatives look set to secure an outright parliamentary majority. (Reporting by Maytaal Angel, writing by David Milliken. Editing by Mike Peacock)