MICHAEL Portillo's shock election night defeat in 1997 came to symbolise the changing of the guard from Tory to New Labour.

Stephen Twigg's victory over the outgoing defence secretary on a huge swing of 17.4% demonstrated that no Conservative, even a Cabinet minister, was safe.

It was later voted the third-best television moment of all time, and the current crop of ministers will be hoping they do not suffer the same humiliation when the results are counted this time round.

So who is most at risk of becoming 2010's Portillo Moment?

The Tories are hoping it will be Children's Secretary Ed Balls, who defends the newly-created Morley and Outwood seat with a notional 8,669 majority.

It would require a swing of almost 10.5% to unseat Gordon Brown's long-term acolyte, but Conservative candidate Antony Calvert has been working the patch hard and Labour slid to fourth place at council elections in 2008.

Chancellor Alistair Darling is also at risk in Edinburgh South West.

With a majority of 7,242 over the Tories, and the Liberal Democrats just 1,000 votes further back in third, the challenge to unseat the Chancellor will come from both sides - though this could work in his favour by splitting the opposition.

Justice Secretary Jack Straw cannot be completely confident of holding his Blackburn seat. As a former Foreign and Home Secretary, Mr Straw's high profile would certainly put him in the Portillo category if local

Tory councillor Michael Law-Riding manages to overturn Labour's 8,048 notional majority on a 9.8% swing.

A uniform national swing of just under 6% would give the Tories a one-seat majority, so other Cabinet ministers looking over their shoulders include Culture Secretary Ben Bradshaw in Exeter, where a swing of 8.7% would wipe out his notional 8,559 cushion.

Scotland Secretary Jim Murphy's 6,657 majority in Renfrewshire East means he would be unseated on a 7.1% swing, while the Tories would take Communities Secretary John Denham's Southampton Itchen seat with a 10.5% swing.

Another high-profile target is Olympics minister Tessa Jowell, who holds a notional 7,853 majority over the Tories in Dulwich West and Norwood.

But with the Liberal Democrats just 500 votes further back, the former culture secretary could benefit from a split in the opposition vote in the same way as Mr Darling.

Lower down the ranks, junior environment minister Dan Norris is in most trouble. He is fighting Somerset North East, where boundary changes give the Conservatives a notional majority of 212 going into the election.

Similar changes put junior transport minister Paul Clark at risk in Gillingham and Rainham - he has a notional majority of 15 - while his departmental colleagues Chris Mole (Ipswich, 5,235) and Sadiq Khan (Tooting, 5,169) would lose their seats with a swing of around 6%. Only unelected Transport Secretary Lord Adonis at the DfT is safe from the voters.

A uniform 6% swing would also wipe out another 16 ministers, including armed forces minister Bill Rammell in Harlow (notional majority 230), Treasury Exchequer Secretary Sarah McCarthy-Fry (Portsmouth North, 315) and schools minister Vernon Coaker (Gedling, 4,335).

Health trio Phil Hope (Corby, 1,517), Ann Keen (Brentford and Isleworth,3,633) and Gillian Merron (Lincoln, 3,806) and environment minister Jim Fitzpatrick (Poplar and Limehouse, 3,823) would be among the casualties,as would work and pensions ministers Jim Knight (Dorset South, 1,812) and Jonathan Shaw (Chatham and Aylesford, 3,289).

Completing the list are communities ministers Shahid Malik (Dewsbury,3,999) and Ian Austin (Dudley North, 4,106), home office minister Alan Campbell (Tynemouth, 5,490), justice minister Claire Ward (Watford, 1,151), energy and climate change minister David Kidney (Stafford, 1,852), Cabinet Office minister Angela E Smith (Basildon South and Thurrock East, 905) and equalities minister Michael Jabez Foster (Hastings and Rye, 1,156).

Former Home Secretary Jacqui Smith (Redditch, 2,163) will also be expecting a nervous evening.