British Prime Minister David Cameron has returned to Number 10 as projections show he is expecting to win with a majority government, according to Sky News.

Despite months of polls forecasting a close-fought contest, a Sky News projection suggests the Conservatives will win 328 seats in the House of Commons, after a collapse in support for both Labor and the Liberal Democrats, giving Mr Cameron a majority of six.

"This is clearly a very strong night for the Conservative party," Mr Cameron said after retaining his Witney seat.

However, the victory still means he will have to govern with a far slimmer majority than John Major in 1992 when the party won with a 21-seat margin.

The Sky News projection puts the Conservatives on 328 seats, Labor on 233, the Scottish National Party on 56, the Liberal Democrats on 8, UKIP on two, Plaid Cymru on three and the Green party on one.