The Labour Party is trailing the Conservatives by a record 20 points, a poll released ahead of the first anniversary of Prime Minister Gordon Brown taking office showed.

The ICM poll in Wednesday's Guardian newspaper puts Labour on 25 percent, down 2 points since the last ICM poll last month, with David Cameron's Conservatives up 4 points on 45 percent.

The Guardian said it was the lowest level of Labour support since ICM polls began in 1984 -- 13 years before Tony Blair led Labour into power after nearly two decades in the political wilderness.

The paper said the poll put the Conservatives on a 20-year high and would give them a landslide victory as big as Labour's in 1997, with some 400 seats.

Labour might be reduced to less than 200 parliamentarians - a shadow of its existing parliamentary majority of some 60 seats.

On Friday, Brown will have been prime minister for exactly one year. He took over from Blair after a decade as his apparently infallible finance minister, producing a constantly growing economy.

The poll comes with Brown and Labour facing a slowing economy, rising industrial discontent and a series of government gaffes over lost personal data.

Brown's personal poll ratings, riding high 12 months ago, have evaporated.

That, coupled with disastrous local election results in May and the loss of a once safe Labour seat in a by-election, have sparked talk of a bid from the party ranks to oust Brown before a national election that must be held by mid-2010.

So far no one has stepped forward.