The Northern Ireland elections concluded at daylight with significant changes in the electoral arithmetic after the DUP regained East Belfast and the Ulster Unionists caused the two big upsets of the campaign by winning South Antrim and Fermanagh South Tyrone.

The election in Northern Ireland began with nationalists holding eight seats and unionists 10 seats. It ended with unionists gaining an extra seat from Sinn Féin leaving the overall result, 11 unionists against 7 nationalists.

The big winners were the Ulster Unionist Party, which had no seats in the House of Commons, while the losers were Alliance and Sinn Féin which each dropped a seat. It means that the unionist MPs, particularly the DUP bloc, could be "pivotal" as DUP leader Peter Robinson had predicted, in ensuring that David Cameron returns to Downing Street as British prime minister.

The results were: the DUP, 8 seats; the Ulster Unionists, one seat; one independent unionist with Lady (Sylvia) Hermon comfortably holding North Down; Sinn Féin four and the SDLP three.

As the counts began the main focus was on East Belfast where Naomi Long of Alliance was hoping to hold the seat she won from First Minister Mr Robinson in 2010. Ms Long increased her vote from 12,839 in 2010 to 16,978 votes, but those additional 4,000 votes weren't sufficient to fend off the challenge from the DUP's Gavin Robinson who polled 19,575 votes.

He was aided by the fact that the Ulster Unionist Party, the Traditional Unionist Voice party and Ukip gave him a free run in East Belfast. Mr Robinson in his acceptance speech did not pay tribute to Ms Long, as frequently is the protocol, while adding, "I'm delighted that the last five long years are over."

It prompted Alliance employment and learning Minister Stephen Farry to say on BBC: "Peter Robinson was more gracious in defeat in 2010 than Gavin Robinson was in victory."

There was an expectation that Sinn Féin's Michelle Gildernew, after winning Fermanagh-South Tyrone by four votes in 2010, would consolidate the seat this time. However, former Ulster Unionist Party leader Tom Elliott, as the sole unionist candidate due to the UUP-DUP pact, caused one of the shocks of the night by taking the seat with a majority of 530 votes. "This is not a green constituency. It doesn't belong to Bobby Sands. It belongs to the people of Fermanagh and South Tyrone and that is who I intend to represent."

Ms Gildernew who held the seat since 2001 said she was “proud and humbled” to have represented “people of all faiths and none” in the constituency.

The other shock of the night was in South Antrim where UUP Assembly member Danny Kinahan ousted the veteran DUP politician, the Rev William McCrea. It was always reckoned it would be close but in the end Mr Kinahan won by more than 900 votes. The other big battle was in South Belfast where the SDLP leader Dr Alasdair McDonnell was viewed as under pressure to hold his seat against the challenge of Jonathan Bell of the DUP and former Sinn Féin lord mayor of Belfast Máirtín Ó Muilleoir.

The SDLP concern was that Mr Ó Muilleor would eat into Dr McDonnell’s vote and thus hand the advantage to Mr Bell. The Sinn Féin vote increased from just over 4,000 votes in the 2011 Assembly elections to 5,400 votes while Mr Bell polled well with 8,654 votes. Dr McDonnell, however, took the seat with 9,560 votes.

Sinn Féin had hopes that Gerry Kelly could take North Belfast against Nigel Dodds of the DUP, and even put out leaflets stating that there were now more Catholics than Protestants in the constituency, triggering accusations of sectarianism against Sinn Fein. Mr Dodds however won quite handily with a majority of more than 4,000.

In Upper Bann the UUP's Jo-Anne Dobson polled well but didn't get sufficiently close to the DUP incumbent David Simpson.

Otherwise, the results went as predicted: the DUP winning Strangford, East Antrim, North Antrim, East Derry and Lagan Valley; Sinn Fein taking West Belfast, West Tyrone, Mid Ulster and Newry and Armagh; and the SDLP winning Foyle and South Down. There remains a possibility that Mr Cameron could achieve an overall majority, but if he does it seems it will be a slight one. Therefore, the DUP with its 8 seats and the UUP with its two could be critical in giving back the keys of 10 Downing Street to Mr Cameron.