The Democratic Unionist party (DUP) is on track to lose three of its eight seats, which would leave Sinn Féin as the Northern Ireland party with most MPs. The DUP lost the Lagan Valley seat vacated by its former leader, Sir Jeffrey Donaldson, who faces sexual offence charges, and suffered a stunning defeat in North Antrim where Ian Paisley lost a seat held by his family since 1970. It also lost South Antrim and had reduced majorities elsewhere. The Traditional Unionist Voice (TUV), Ulster Unionists and Alliance were poised to take the DUP seats but the symbolic winner will be Sinn Féin which retained its seven seats and is on course to complete a hat-trick as the biggest party in local government, the Stormont assembly and Westminster. The DUP leader, Gavin Robinson, fended off a challenge from Alliance’s Naomi Long in East Belfast but that could not conceal a devastating election for unionism’s biggest party. Its record on Brexit and other missteps left it squeezed between moderate and hardline rivals. In an astonishing reversal in North Antrim, Paisley, the son and namesake of the DUP’s late founder, came second to Jim Allister of the TUV, who blamed the DUP for post-Brexit checks on goods coming from Great Britain, which he said weakened Northern Ireland’s place in the UK. “This is a momentous outcome and is the end of an era and a dynasty,” said Allister. “Unionism does need to regroup in the light of what has happened and the DUP needs to carry the responsibility for their losses.” Reform had originally backed the TUV but after becoming leader, Nigel Farage endorsed Paisley, a Brexiter ally. “I might say I’m here in spite of you, Nigel,” said Allister. Paisley conceded defeat and said the tides of life ebbed and flowed. Sorcha Eastwood of Alliance won Lagan Valley in a historic swing for what used to be a unionist bastion. The DUP fielded Jonathan Buckley to replace Donaldson, who had held the seat for decades and stepped aside after being charged with sexual offences, which he denies. Eastwood called it a “huge achievement” for her party. “I’m a Lagan Valley girl born and bred, and this has been in our heart for a long time and I’m just delighted,” she said. Alliance’s joy was tempered by its deputy leader, Stephen Farry, losing his seat in North Down to the independent unionist Alex Eastwood. The Ulster Unionist candidate Robin Swann, a former Stormont health minister, ousted the DUP’s Paul Girvan as MP for South Antrim. The Social Democratic and Labour party retained its two MPs, Colum Eastwood and Claire Hanna. Sinn Féin held its seven seats and whittled the majority of the East Derry seat held by the DUP’s Gregory Campbell, prompting a recount. The republican party’s leader, Michelle O’Neill, called it a “tremendous result right across the board”.