TOMORROW'S General Election will be won or lost in around 200 marginal constituencies across mainland Britain. Political Editor Graham Dines previews the battleground seats in the East of England and points out some seats elsewhere to watch on the night.

TOMORROW'S General Election will be won or lost in around 200 marginal constituencies across mainland Britain. Political Editor Graham Dines previews the battleground seats in the East of England and points out some seats elsewhere to watch on the night.

ESSEX

Braintree: Majority 358 (Labour). This is Labour's second most vulnerable seat in the East of England, represented since 1997 by Alan Hurst. Putting it bluntly, if Tory Brooks Newmark does not succeed at his second attempt, the Conservative Party as we know it will be finished.

Colchester: Majority 5,533 (Liberal Democrat). Labour's vote in the garrison town has collapsed in the past eight years, making this a two-horse race between the 2001 protagonists Bob Russell (Lib Dem) and Kevin Bentley (Conservative). Voters have to decide which outcome would give Tony Blair the bloodiest nose - a Tory victory or the continuing presence of a Liberal Democrat.

Castle Point: Majority 985 (Conservative). The posh name for Canvey Island and surrounding towns and villages, this was one of only two Tory gains in the region in 2001. It is one of three targets for Labour in the region - the others being Bedfordshire South-West and Norfolk North-West - but the Conservatives should prevail.

Harlow: Majority 5,228 (Labour). An outside bet for the Conservatives, who need a swing of 6.51%. But Labour's vote slumped at the 2001 election, the party performance in council elections has been calamitous, and there is hostility to the expansion of nearby Stansted airport and the building of thousands of houses on surrounding green fields.

Harwich: Majority 2,596 (Labour). Ivan Henderson, the first Labour MP in Harwich's history was elected in 1997 and he won again in 2001. His fate largely depends on whether he or Tory Douglas Carswell is better able to get out their party's core vote.

SUFFOLK

Ipswich: Majority 8,081 (Labour). Although Labour's cushion was halved in the 2001 by-election, the General Election result in the guide figure, meaning the Tories need a swing of 10.46%. But a good performance by the Conservatives in the county town where demographics are rapidly changing would create the platform from which to predict a Tory gain in four years time.

NORFOLK

Great Yarmouth: Majority 4,564 (Labour). This could be a better bet for the Tories than Harwich, even though the swing required is 5.65%. The town has some of the worst depravation in East Anglia, but the leafy acres stretching towards the Broads may be enough to see the Conservatives scrape home.

Norfolk North: Majority 483 (Liberal Democrat). Inept Tory targeting of the relatively safe Labour seat of Waveney in 2001 allowed the Lib Dems to snatch this seat centred on Cromer from the Conservatives' Chief Executive David Prior. Lib Dem Norman Lamb is a popular MP and will be very hard to shift this time.

CAMBRIDGESHIRE

Cambridge: Majority 8,579 (Labour). A meltdown in the Tory vote since they last won here in 1987 makes this a Labour-Lib Dem fight, and it is one of the Lib Dems' target seats in East Anglia. They hope academia's anger over the Iraq War and tuition fees will help them pull off the seemingly unlikely 10.1% swing needed for victory

Peterborough: Majority 2,854 (Labour). Another Tory "must-win" seat and don't be surprised if Stewart Jackson wins at the second attempt to defeat the controversial Helen Clark (formerly Brinton)

HERTFORDSHIRE

Hemel Hempstead: Majority 3,742 (Labour). The new town saw Labour increase its majority last time, but the Conservatives have put in an energetic campaign and the result is likely to be a few hundred either way.

Watford: Majority 5,555 (Labour). The Lib Dems were third in 2001 but this is their top target seat, with Sal Brinton determined to capitalise on her party's victory in the only directly elected mayoral contest in the region. This is the one seat in the East where Labour fears the Tories will be elected "by the back door" as its support haemorrhages to the Lib Dems.

Welwyn-Hatfield: Majority 1,196 (Labour). The Tories need just a 1.41% swing - and all the reports from Welwyn Garden City and millionaires row at Brookmans Park suggest that junior minister Melanie Johnson will be a major casualty on tomorrow night.

ELSEWHERE

Northamptonshire and Dorset contain some of Britain's most marginal seats. Kettering (Labour majority 665), Northampton South (Lab 885), and Wellingborough (Lab, 2,335) are top Tory targets in Northants while down on the South Coast, Mid Dorset & Poole North (Lib Dem, 384), Dorset South (Lab, 153) and Dorset West (Tory Shadow Chancellor Oliver Letwin, 1,414) could all change hands.

Other seats to look out for: Devon West & Torridge, where Boris Johnson's 60 year-old father is attempting to overturn a Lib Dem majority of 1,164; Bethnal Green & Bow, a battle between Respect's George Galloway and Oona King for Labour; Ilford North, where the Tories are odds on to overturn a 2,115 majority in this North East London division; Hornchurch (Lab, 1,482); Enfield North (Lab, 2,291); Surrey South West (Tory majority over Lib Dems, 861); and Cheadle in Greater Manchester, the closest race in 2001 where the Lib Dems won by just 33 from the Tories.

As results come in, Labour will build up a massive initial majority as their heartland seats in the North, Midlands, London and Scotland are declared ahead of those in the shires. All three results in the City of Sunderland should be known before midnight

First pointer to Tory chances is likely to be Torbay, where the Lib Dems increased their majority last time from 12 to 6,708. Any cut in this figure, or indeed a Tory gain, will be worrying indeed for Charles Kennedy.

Another early declaration on the Conservatives' hit list is Thanet South in Kent, where Labour is defending a 1,792 majority.