Gordon Brown's first anniversary as prime minister was marked by a trouncing in the Henley by-election, with Labour limping into fifth place behind the Greens and the far-right BNP and its candidate losing his deposit.
The disastrous night for Labour was an excellent result for David Cameron's Conservatives, whose candidate John Howell won the seat with an increased 57 percent share of votes cast.
The Liberal Democrats came second with a 27.9 percent share.
"It's a terrible result," Labour Health Minister Ben Bradshaw told BBC radio on Friday, saying voters were reacting to economic events beyond the control of the government.
"When people start feeling the pinch . because of rising fuel and food prices, they take out their anxiety and frustration on the incumbent government."
Labour had never been expected to win the seat, one of the safest Conservative strongholds in the country, held since 2001 by Boris Johnson, whose election as Mayor of London last month triggered the election.
But the collapse in the Labour vote - down to just 3.1 percent from 14.7 percent in the 2005 election when it came third - could further weaken Brown's standing in his party after a calamitous first year as prime minister.
It comes just over a month after the by-election loss of the safe Labour constituency of Crewe and Nantwich.
A poll in the Daily Telegraph added further grim reading for Brown, saying he was now regarded as a liability to Labour by two-thirds of voters.
The YouGov survey found that only 16 percent of those asked thought Labour would win the next election - expected in 2010 - with 67 percent predicting a Conservative victory.
