As the night unfolds, here is a guide from political editor Annabelle Dickson of a few of the seats, both locally and nationally, to keep an eye on.

Ipswich: Conservative Ben Gummer has a big fight on his hands to hold this seat. If he does, it will be seen as a huge victory for the Conservatives.

Clacton: One of UKIP’s two seats. All eyes will be on Douglas Carswell to see if he can consolidate his by-election victory

Waveney: Like Norwich North this is a key Tory versus Labour marginal. David Cameron has visited the seat twice this year.

Great Yarmouth: A key target for the UK Independence Party, but also in the sights of Labour and the Conservatives.

Norwich North: Currently held by the Conservative Chloe Smith, but the polls suggest it is going to be a very close contest with Labour’s Jessica Asato. Psycologically for both parties, it is a key seat.

Norwich South: Currently a Liberal Democrat seat. One Labour must win if the party is to return to power. But also a key target for the Green Party.

Glasgow East: The SNP need a huge swing to take this seat which would be a huge blow for Labour north of the border.

Gordon: The Lib Dem seat former SNP leader Alex Salmond has in his sights.

Inverness, Nairn, Badenoch & Strathspey: Chief secretary to the Treasury and Lib Dem Danny Alexander’s seat. Another one the SNP could take.

Heywood & Middleton: UKIP came second by only 617 votes in last year’s by-election.

Wirral West: Conservative Esther McVey holds this seat. Crucial for Labour if it is going to have a good night.

Sheffield Hallam: The Labour Party has put plenty of resources into trying to unseat Lib Dem leader Nick Clegg, for whom a defeat would fire the starting gun on a leadership contest.

Boston & Skegness: Key UKIP target seat that would require a massive swing to unseat the Conservatives.

Great Grimsby: Key target for UKIP and the Conservatives.

Arfon: A Plaid Cymru seat which Labour needs to take back. A good bellwether of how the nationalist vote is holding up in other devolved regions.

Northampton North: Voters have always elected an MP from the party that has gone on to win the general election. A Conservative seat being targeted by Labour.

Solihull: Lib Dems have a majority of just 175. It is the sort of seat Conservatives have to win if they are to get anywhere near a majority.

Bristol West: Similar to Norwich South – a Lib Dem seat which is a key target seat for the Greens.

Dartford: In every election since 1964 it has returned an MP from the same party that has gone on to form the government.

Rochester & Strood: Key seat for UKIP. Mark Reckless, who defected from the Conservatives to UKIP, is under threat.

Thanet South: The seat Nigel Farage needs to take if he is to remain leader of UKIP. The Tories have a sizable majority so it would require a big swing.

Thurrock: A Tory, Labour, UKIP contest. Another big seat for UKIP. Tory Jackie Doyle-Price has a majority of just 92.

Hampstead & Kilburn: Key Labour versus Tory marginal. Labour’s Glenda Jackson won a majority of just 42 votes last time.

Fermanagh & South Tyrone: The most marginal seat in the whole of the UK. Michelle Gildernew is defending a majority of just four. The DUP is not fielding a candidate and urging its supporters to vote for the Ulster Unionists. The result could be very close once again.

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