The seats that hold the keys to Downing St

It's all over bar the counting. Frank Millar suggests what to look out for in the results tonight

It's all over bar the counting. Frank Millar suggests what to look out for in the results tonight

Possibleupsets

Were you up for Portillo? For many people Stephen Twigg's defeat of Michael Portillo - then blue-eyed boy of the Thatcherite right - was one of the defining images of Britain's brutal ejection of John Major's government in the general election of 1997.

When Tony Blair won his second historic landslide in 2001 the Tories ended up with a net gain of just one seat in an election marked by an absence of memorable defeats. Election night 2005 promises to be different again.

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If the polls are broadly correct we are not going to witness a succession of senior ministers buried in the rubble of an electoral revolution. However, some big names in each of the main parties could be at risk, and vulnerable ministers include Stephen Twigg himself (Enfield Southgate), Ruth Kelly (Bolton West) and Alistair Darling (Edinburgh South West). Home secretary Charles Clarke looks safe in Norwich South, but could be troubled by a Liberal Democrat upsurge.

And foreign secretary Jack Straw is taking nothing for granted in Blackburn which, with its large Muslim population, could also be hit by a large anti-government swing.

There are high-profile personality battles elsewhere over some of the big election issues. Regional variations and strong local factors could defy trends and spring surprises. And one other thing is certain.

A better than predicted swing to the Conservatives means a lot of sitting Labour MPs could be about to rediscover something they haven't known in the last three elections - the pain of losing their seat.

Mainopposition

If the Conservatives really are going down to a third successive defeat, attention will switch immediately to the question of Michael Howard's survival. The Tories won just 162 seats last time. The most modest assessment says Michael Howard has to at least surpass Michael Foot's disastrous 1983 tally of 209 to have any reason to stay on. However, a look at the figures shows the uphill battle facing a Conservative Party so long considered the natural party of government. And the key measure of how well or badly Howard's "dog whistle" campaign has played with the electorate will be the Tory share of the vote.

In June 2001 under William Hague, the Conservatives won just 31.7 per cent of the vote and 166 seats. Triumphant Labour took 412 seats with 40.7 per cent, and the Lib Dems 52 on 18.3 per cent. Post-devolution, the number of Scottish seats has been reduced from 72 to 59, reducing the number of MPs in the next House of Commons to 646.

Consequently, the number of seats required for a party to form a majority government is now 324. Tony Blair could lose his majority with the loss of just 79 seats. However, for Michael Howard to form the next government the Tories need to win 158 seats.

As the swingometer tells it:

The swing needed for Conservatives to deprive Labour of overall majority - 6.3 per cent.

Swing needed for Conservatives to become largest party - 8.2 per cent.

Swing needed for Conservatives to win overall majority - 10.3 per cent.

Electionturnout

Turnout fell in 2001 to an all-time low of 59.4 per cent.

There are suggestions that Labour could be back this time with less than 40 per cent of the available vote. Against that, with Tony Blair and Michael Howard arousing strong feelings, some of the polls suggest the turnout could be up this time. While Labour is calling this the "turnout election", the 12-point fall from 1997 didn't dent Labour's majority in 2001. Polling experts say a further drop is unlikely to differentially affect the parties.

 Partytargets

Topping the list of Conservative targets are Cheadle, Dumfries&Galloway, and Dorset South. They will really be starting to enjoy themselves, and Blair's majority will be shrinking, if they start winning in places like Hove (Lab majority 3,171) and Putney (target seat 52) where Labour is defending an 8.1 per cent lead. And we are into the territory of Labour losing its overall majority if seats like Watford, Corby, Leeds North West and Edgbaston start going Howard's way.

The Liberal Democrats' number one Labour target is Cardiff Central, where the large student population may have rallied to Charles Kennedy's assault on Blair over the war and university fees. Large defections by disillusioned Labour voters could also boost Lib Dem hopes in places like Oldham East & Saddleworth, Bristol West, and Birmingham Yardley. Also keep an eye on Cambridge, where Kennedy drew big crowds and which Blair visited this week in defence of a Labour majority of 8,579. However, eight of the top 10 Lib Dem targets are Conservative held, including Taunton, Surrey West, Eastbourne and the Isle of Wight.

And of course Charles Kennedy also has a "decapitation strategy" by which he hopes to topple the present Conservative leader Michael Howard (Folkestone & Hythe) and the man tipped to succeed him, David Davis (Haltemprice & Howden). If successful, Kennedy's ambitious plan could also claim shadow chancellor Oliver Letwin's scalp in Dorset West.

Regionalbattlefields

The southeast is England's largest region, where the battle between the Conservatives and Liberal Democrats will be most keenly fought.

If the Lib Dems are truly thinking to replace the Tories as "the real opposition" they'll want to build on past gains, looking to seats like Surrey South West and Maidenhead. The Conservatives, on the other hand, will be hoping to recover past losses in places like Newbury, Romsey and Guildford.

The southwest should provide a fascinating contest, with only about 16 of 51 constituencies considered safe for any party, in the most genuinely three-party region in England. If the Conservatives are winning anywhere, it must be in the west midlands, which in the past has swung more strongly behind the winning party. In the east midlands. Labour will be hoping to regain Leicester South, lost to the Lib Dems in a byelection last year on a surge of anti-war sentiment. Further north, meanwhile - having left UKIP and formed his own party, Veritas - can Robert Kilroy-Silk ride the tide of Eurosceptic opinion to take Erewash (majority 6,932) off Labour? In Yorkshire and the Humber Labour is safely rooted in the cities of Leeds and Bradford. But the region includes a significant and growing number of marginals including Brigg & Goole, Selby, Leeds North East and Leeds North West, Shipley and Colne Valley. Particular attention will focus on Keighley, one of Yorkshire's key barometer seats, where Labour's Ann Cryer has upset some of the Asian community and Lib Dems might decide to help the Tories to see off a serious effort from BNP leader Nick Griffin.

The northwest of England will provide another test of Muslim opinion and disparate voting priorities as the Conservatives battle to recover in some 20 marginals, many of which they lost in 1997. However, they will need to be doing very well nationally to make a big impact here. Meanwhile, will Liverpool Riverside deliver a new all-time low turnout, and can the BNP build on local election gains since 2001? With 23 of its 30 seats classified "safe" for Labour, interest in the northeast will focus, surprisingly, on Tony Blair's constituency of Sedgefield where Reg Keys - father of Lance Cpl Tom Keys, one of the royal military policemen killed in Iraq - is leading a deeply personal campaign on the question of the war and Mr Blair's credibility.

In Wales, Conservative targets include Monmouth (held by Labour) and Brecon & Radnorshire (Lib Dem), as well as Clwyd West, Preseli Pembrokeshire and the Vale of Glamorgan (all Labour), while Cardiff Central and Ceredigion are the Lib Dems top two targets. Plaid Cymru is challenging Labour in Ynys Mon and Llanelli after losing ground in the last Welsh Assembly elections.

In Scotland, meanwhile, Inverness, Nairn, Badenoch & Strathspey provides the country's only real three-way marginal with Labour, Lib Dems and the SNP in contention. Polls this week suggest the Lib Dems may benefit from anti-war sentiment. This could be bad news for SNP leader Alex Salmond who wants to at least equal the party's 1997 tally of six Westminster seats.

Predictions are difficult because of the boundaries review but key Tory targets include Dumfries&Galloway (which merges the party's only seat last time), Moray (held by SNP) and Argyll & Bute (LD). Hoping to win Inverness, the Lib Dems also have their sights on Labour's Dunbartonshire East, Aberdeen South and Edinburgh South, while the SNP is targeting Labour in Dundee East, Ochil & South Perthshire as well as (with the Tories) Dumfries & Galloway.

Thewar/London

Rose Gentle, whose son Gordon was killed in Iraq, is opposing armed forces minister Adam Ingram in East Kilbride. But the biggest battle over the war is being fought on the streets of London's East End, in Bethnal Green & Bow, where the ghost of Old Labour, Respect candidate George Galloway, hopes to unseat Labour's Oona King. Ms King, who has one Afro-Caribbean and one Jewish parent, is defending a majority of 10,057 against the man thrown out of the Labour party after accusing Tony Blair and George Bush of invading Iraq "like wolves". Muslim fundamentalists have branded him a "false prophet" but Galloway scents the possibility of a sensational return to Westminster. And it is difficult to read the play of the politics of race in this constituency, which actually saw Labour's vote fall and the Conservative vote increase at the moment of Mr Blair's greatest triumph in 1997.

Watch how the politics of race might play, too, in Barking, where the BNP is making a big effort against children's minister Margaret Hodge, and in Brent East where Labour's Yasmin Qureshi is hoping to reclaim the seat won by Lib Dem Sarah Teather in the 2003 byelection.

Key Tory targets in the capital include Hammersmith & Fulham and Ilford North. Gordon Brown will be anticipating an early succession if Conservative gains in places like Wimbledon send Tony Blair's majority tumbling, while the majority should be gone altogether if the Tories scale the barricades in their 122nd target seat in Battersea.