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With polls predicting the closest UK general election result in decades, the outcome of each constituency will be closely scrutinised. Here are some seats that will offer clues to the national outcome.
Conservative seats targeted by Labour
Nuneaton (Con hold)
The Tories won the Midlands seat of Nuneaton from Labour in 2010 with a 7.2 per cent swing. Labour’s Vicky Fowler had been hoping to take it back from Conservative MP Marcus Jones, overturning his majority of 2,069.
A key three-way marginal. The Conservatives took the seat from Labour in 2010 with a majority of 1,936. An Ashcroft poll in January indicated that Liberal Democrat support had collapsed, putting Labour in the lead.
Vale of Glamorgan (Con hold)
In this seat, just outside Cardiff, an Ashcroft poll in February put Labour at 32 per cent and the Tories on 38 per cent. The Labour figure was right, but the Tories reached 46 per cent and a majority of 6,880.
Wirral West (Lab gain)
The seat of Esther McVey, employment minister, fell to Labour. Name recognition did not help the Tory incumbent prevent a narrow victory of just 417 votes.
Education secretary Nicky Morgan has a majority of 3,744. The seat is a key marginal, having been won by the party that received the most seats at every general election since February 1974.
Hendon (Con hold)
Tory MP Matthew Offord had a majority of just 106, making this north London seat a must-win for Labour. He is now a clear 3,724 votes ahead.
Lib Dem seats targeted by Tories
Lib Dem MP Jeremy Deane is standing down, and this Somerset seat is high on the list of Conservative targets. Candidate Rebecca Pow needs to overturn a majority of 3,993.
Somerton and Frome (Con gain)
Another West Country seat with a departing Lib Dem incumbent. David Heath’s majority was 1,817; a poll in September showed the Tories comfortably in the lead, a margin they maintained, taking the seat by 20,268 votes.
Nick Harvey won with a majority of 5,821 in 2010. But he is standing down this time and the seat is a lot less safe. The latest Ashcroft poll gave the Tories 38 per cent compared with the Lib Dems on 31 per cent.
Lib Dem seats targeted by Labour
Hornsey & Wood Green (Lab gain)
Lib Dem minister Home Office Lynne Featherstone fell in a fierce battle with Labour candidate Catherine West in this north London seat. Ms Featherstone had a majority of 6,875 that turned into a Labour majority of more than 11,000.
Brent Central (Lab gain)
Sarah Teather, once a young Lib Dem star, stood down, and Labour’s Dawn Butler, needing to overturn the majority of 1,345, won by a margin of 19,649.
Rochester and Strood
Mark Reckless famously defected from the Tories to Ukip last year and survived a by-election in November, winning a majority of 2,920. But he is not a shoo-in to keep the seat, which Conservative Kelly Tolhurst is forecast to take back.
Nigel Farage, Ukip’s leader, has said he will resign within 10 minutes if he does not win this seat. Polling right up the election eve suggested the Tory vote was holding up with Craig Mackinlay tipped to win the seat held by his predecessor. But pollsters have admitted their modelling may not be picking up support for the smaller parties correctly and Mr Farage could yet defy any trend in waning support for Ukip given his high profile.
The battle for Scotland
Kirkcaldy and Cowdenbeath (SNP gain)
A sign of how likely it was to be a very, very bad night for Labour in Scotland came when the party lost the seat being vacated by former prime minister Gordon Brown. Until Thursday it had been the third safest in Scotland in terms of the incumbent’s margin of victory over the SNP in 2010.
Paisley and Renfrewshire South (SNP gain)
Douglas Alexander, the shadow foreign secretary and head of Labour’s national election campaign, had represented this constituency since 1997. But this was yet another ultra-safe seat that the SNP had been tipped to win with Mhairi Black, a politics student at Glasgow University, the usurper. The 20-year-old becomes the youngest MP at Westminster.
Inverness, Nairn, Badenoch and Strathspey (SNP gain)
Another Alexander, this time Danny, the Lib Dem’s first secretary to the Treasury, was an odds-on certainty to lose his seat, according to the bookmakers — and duly did so. His SNP rival, Drew Hendry, used Mr Alexander’s role as deputy to Tory chancellor George Osborne as one of his main points of attack and won by 10,809.
Gordon (SNP gain)
This constituency in a largely prosperous part of Aberdeenshire voted 60-40 against independence last year. But the chosen target seat for Alex Salmond sent the former SNP party leader and Scottish first minister back to Westminster to lead the Nationalist charge.
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