LONDON (AFP) - Counting began after polls closed in a by-election in southern England on Thursday, with a new political blow to Prime Minister Gordon Brown expected, as he marks his first year in power.

The affluent, rural seat of Henley, near Oxford, came up for grabs after the sitting member of parliament, Boris Johnson from the opposition Conservative Party, won election on May 1 as London’s new mayor.

But anything other than a Conservative win would be a shock, as Johnson, who represented the constituency from 2001, had a majority of 12,793 at the last general election in 2005 with 53.5 percent of the vote.

Attention will be focused on the size of the Conservative majority and how many votes the candidate for Brown’s governing Labour Party polls, as an indicator of current support for the two main parties.

Labour is expected to come in third, behind the Conservatives and Liberal Democrats, providing Brown with an unwelcome, although not unexpected, present for his first anniversary as prime minister on Friday.

Two bookmakers even had Labour’s candidate at odds-on to lose his 500-pound (630-euro, 990-dollar) deposit, which would happen if he fails to secure more than five percent of the total votes cast.

David Cameron’s Conservative Party has polled well in local elections in England and Wales on May 1, taken the London mayoralty and a formerly safe Labour seat in a by-election on May 22.

An ICM/Guardian poll published Tuesday put the centre-right party 20 points ahead of centre-left Labour, enough for a healthy parliamentary majority if repeated at a general election.

Courtesy of;http://ca.news.yahoo.com/s/afp/080626/world/britain_politics_vote_henley