The consequences of last week’s general election on the shape of the House of Commons are most visible on the government benches, which can no longer accommodate the multitude of Conservative MPs.

Yet the changes on the opposition benches were more striking as MPs debated the queen’s speech on Thursday, with Labour and the Liberal Democrats shrunken and despondent, while the resurgent Scottish National Party (SNP) was alight with confidence and purpose.

The DUP is diminished in number and in influence, now surplus to requirements for the Conservatives and no longer the only party from Northern Ireland to take their seats in the Commons.

SDLP leader Colum Eastwood, who was elected last week along with Claire Hanna and the Alliance’s Stephen Farry, wasted no time in making a maiden speech on Thursday that alerted MPs on all sides that a formidable new voice has arrived at Westminster.

He told the chamber that he stood there as an Irish nationalist. “In fact I stand here because I’m an Irish nationalist, not in spite of it, because I believe that every single person in all of our constituencies needs to be properly and fully represented. So I’m glad to be here.

“But we are not narrow nationalists. We come from the tradition of Parnell and Hume. Our vision is big and it is broad, and our mission is to unite all of our people, not divide them any further. So we intend to represent nationalists, unionists and everybody else.”

After that assertion of the contrast between the SDLP’s approach and Sinn Féin’s abstentionism, Eastwood turned his focus on the DUP, whose MPs were sitting on the bench below him.

He described Boris Johnson’s approach to Brexit as reckless, accusing the prime minister of driving a coach and horses through the Belfast Agreement.

Brexit agenda

“I’m glad to see now that the DUP are very concerned about the checks between this island and our island. It’s a pity they didn’t think about that when they drove the Brexit agenda, when they rejected Theresa May’s deal, and now we’re in a situation that none of us are happy with. We’re in a situation that every one of us should be trying to reverse and reject.”

A few minutes earlier the DUP’s Sammy Wilson had praised Johnson for delivering Brexit, but asked the prime minister to use the authority his 80-seat majority gave him to wring some changes from the EU over the next year.

Nothing the prime minister negotiates next year will change the withdrawal agreement bill MPs will debate on Friday, and that will pass all its stages in parliament by the middle of January. The bill implements the Northern Ireland protocol that will oblige Northern Ireland to follow EU regulations and customs rules after Brexit, creating a regulatory barrier in the Irish Sea. The DUP’s new leader at Westminster, Jeffrey Donaldson, appeared to acknowledge that the game was up, asking the government to take steps to limit the damage.

“Many of the issues that need to be addressed to mitigate the impact of the consequences of the withdrawal agreement are internal to the United Kingdom. And there are measures that the government can take to mitigate the impact on the Northern Ireland economy and Northern Ireland business. And what we’re seeking from the government is a commitment to do that so that it benefits the whole of the United Kingdom.”

The queen’s speech promised legislation to protect former soldiers from “vexatious” prosecutions for actions they took while on active service. The measure is popular among Conservative backbenchers and has long been championed by the DUP.

Can of worms

However, Eastwood warned the government about the can of worms it was preparing to open. “In 1972, 14 innocent civil rights marchers were gunned down by the British army on the streets of Derry. Is prosecuting those veterans vexatious? No it is not.

“We will resist this attempt to undermine our peace process and our political progress and this insult to victims, all of the victims of our terrible, terrible past and the opportunity that has been denied to them since 1998 to find full truth and full justice.

“We stand by every single one of those victims no matter who the perpetrator was. And people on the benches opposite need to understand this: if you begin with an amnesty for the British army you will end up with an amnesty for everybody.”

Ian Paisley had a friendly exchange with Johnson earlier over the prime minister’s enthusiasm for a bridge between Scotland and Northern Ireland, a proposal Wilson also praised as a concrete symbol of the integrity of the Union.

“They want to build a bridge from Scotland to Northern Ireland,” Eastwood said. “Well, they’d be much better suited building a decent road from Belfast to Derry.”