Jon Tonge said Arlene Foster is in the DUP car but it is being driven by Nigel Dodds

ARLENE Foster has "responsibility without power" as her party's focus continues to shift from Stormont to Westminster, an expert on the DUP has claimed.

University of Liverpool academic Jon Tonge said the former first minister was increasingly being eclipsed by her deputy Nigel Dodds.

Mrs Foster was flanked by Mr Dodds and three other DUP MPs at Stormont on Monday as she announced that her party could not accept a reported deal on the border between the EU and British government.

Former Sinn Féin education minister John O'Dowd described the image as "striking", while one newsreader remarked that the DUP leader appeared nervous as she read her statement.

Professor Tonge said he could not decide whether Monday's events were "cock-up or conspiracy".

"It's possible the EU and Irish government misunderstood how far the British government would go in terms of regulatory convergence and all-island relations, and maybe Arlene was nervous because the rug had been taken from under her feet," he said.

"The more conspiratorial theory is that it was all a bit of choreography and that the British government knew perfectly well this was unsellable to the DUP – Nigel Dodds was fully aware of what was going on and the British government can now use the DUP as a battering ram to open up a bespoke UK-Irish government free trade deal."

However, Prof Tonge was more certain about the DUP leader's predicament – and he said the situation was unlikely to change in the foreseeable future.

"Power is draining away from Stormont and has been gravitating to Westminster ever since June 8, so it's inevitable that Nigel Dodds will be leader in all but name because that's where the power base is," he said.

"Arlene Foster has no political clothes at present because Stormont is suspended and she's dependent on Sinn Féin for restoring power-sharing, and there's no immediate prospect of that."

The author of DUP: From Protest to Power said that while Mrs Foster was the "unquestioned leader", she had "responsibility without power".

"Mrs Foster is in the car but it's being driven by Nigel Dodds," he said.