What do the votes for abortion and gay marriage in Northern Ireland mean for devolution?

Two landmark votes by MPs to extend gay and abortion rights in Northern Ireland have reopened the debate about when devolved government will be restored to the province.

The Commons voted by big majorities on Tuesday to legalise gay marriage and widen abortion rights. The decision means the UK government will have to change the law in Northern Ireland if the Stormont assembly has not sat by 21 October. It has been mothballed since January 2017 following a dispute between the Democratic Unionist Party and Sinn Fein.

Some UK ministers hope the intervention by MPs will give new impetus to peace talks aimed at restoring the Belfast assembly and power-sharing executive, which have been running for 10 weeks. There have been some flashpoints but no breakdown and ministers are cautiously optimistic that some progress has been made.

The two amendments, added to a bill to delay elections to the assembly, pose a dilemma for both the DUP and Sinn Fein. The socially conservative DUP has criticised what it sees as an unwarranted interference by Westminster in two matters that should be decided in the province. Sinn Fein believes it was inevitable the UK parliament would at some point address equality issues that it says have been blocked by the DUP.

In the short term, the Commons intervention might give Sinn Fein an incentive not to restore self-government, since the greater rights for gay people and women rights are now in the pipeline. Privately, it might suit the DUP for two boulders on the road to a harmonious devolved administration to be cleared out of the way by Westminster.

However, parliament’s decision could also be seen as a step towards direct rule from Westminster, which could have implications for other issues if no agreement can be reached on restoring Stormont.

The changing of the guard at Downing Street will add another layer to the fraught debate. Boris Johnson, the clear frontrunner to succeed Theresa May, will inherit her dependence on the DUP for a shrinking Tory Commons majority, which would go down from four to three if the Liberal Democrats win the 1 August by-election in Brecon and Radnorshire.

The confidence and supply agreement struck two years ago has expired and so renewing it will be near the top of the new prime minister’s in-tray. That will probably mean finding some extra Treasury money for projects in Northern Ireland; the first agreement was worth £1bn to the province.

Johnson was received with adulation when he addressed the DUP’s conference last November. He attacked May’s withdrawal agreement and called for the Irish backstop to be junked. “It is absolutely vital that we keep this partnership going,” he said.

He may soon need those words to come true. The DUP’s 10 votes could prove crucial if prime minister Johnson tried to forge a Commons majority for a revised EU deal. They are worth more than that, since many Tory Eurosceptics take their cue from the DUP.