Harrow West has stayed red after incumbent Labour MP Gareth Thomas won a narrow victory, netting 21,885 votes.
He secured a reduced majority of 2,208 over first-time Jewish Conservative candidate Hannah David, who polled 19,677.
UKIP pushed its way to third place with 2047 votes, relegating the Liberal Democrats.
In the 2010 general election Mr Thomas won a majority of 3,143.