Published: 1:26 PM December 6, 2017 Updated: 6:09 PM September 17, 2020

Theresa May has been warned no Brexit deal is "reckless and dangerous", as "utterly ruthless" dissident republicans would target border officials.

Independent MP Lady Hermon (North Down) said a hard border would inevitably exist between Northern Ireland and the Republic if the UK and EU failed to agree a deal.

She said the UK government had a "moral" responsibility to take care of all officials, including those from HM Revenue and Customs, Police Service of Northern Ireland (PSNI) and UK Border Force.

Lady Hermon has attracted support from Conservative MPs for her European Union (Withdrawal) Bill proposal - new clause 70 - which seeks to preserve the principles of the Good Friday Agreement in the legislation.

The Bill seeks to transfer European law into British law, and says it may not amend or repeal the Northern Ireland Act 1998 - which is underpinned by the agreement.

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Lady Hermon said she believed the wording was technically correct but questioned what it meant, insisting the language must be clearer in stating its commitment to the principles of the agreement.

Lady Hermon recalled that her late husband Jack had to attend almost 100 funerals for officers killed during his 10 years as chief constable of the Royal Ulster Constabulary.

She said her husband supported the Good Friday Agreement despite the constitutional consequences of Sinn Fein being involved in the Executive, adding that it had brought stability and peace to Northern Ireland which has benefited the UK, the Republic and the EU.

She said: "We have normality in Northern Ireland, we have peace, and we undoubtedly have people alive today that would not otherwise have been alive.

"May I just say ever so loudly and strongly to senior members of the Conservative Party - I do not want to hear them or see them on television talking about pushing ahead with no deal. Let's just move on from no deal.

"It's an absolute nonsense, it is so reckless and so dangerous because dissident republicans... are active, they're dangerous, they're utterly ruthless.

"And if I had a child or grandchild who hadn't chosen a different career - I don't have any grandchildren by the way, I've got two children who have chosen other careers, it won't be politics, sadly, because we do need leadership in Northern Ireland, we do need young people coming to politics - I would not be encouraging them to join UK Border Force or HMRC in the event of no-deal Brexit because we'll inevitably have a hard border.

"It must be a moral responsibility, a duty on this Government to take care of all personnel, all officials in HMRC, in the Police Service of Northern Ireland and UK Border Force.

"In the event of no deal, we certainly face a hard border and dissident republicans will regard PSNI officers, HMRC officers and UK border officials as legitimate targets.

"I don't want that on my conscience and I don't believe for one moment the Prime Minister wants that either, or the Government.

"So, for senior members of the Conservative Party, I plead with them to stop the nonsense of talking up a no deal."

Conservative former cabinet minister Ken Clarke said Mrs May's apparent border agreement, vetoed by the DUP, seemed to show she shared Lady Hermon's concerns.

He said: "You can't have an open border without having some regulatory convergence and customs convergence both sides.

"That all came to an end when the DUP vetoed it, which makes it extremely important - more than it was - that [Lady Hermon's] amendment is now put into the Bill to make sure we're not backsliding."

Tory former minister Anna Soubry said she would vote for Lady Hermon's amendment, unless she hears "some good reason why I shouldn't vote for it".

"I think it is eminently sensible and I think we are now reaching a point in all of this when, frankly, people have just got to be big and strong and brave and say they will do what they believe is right and they will put the interests of our country - and that's the United Kingdom - before political allegiance and everything else," she said.

"This is bigger and more important than anything else."

Ms Soubry said there were still MPs "banging on about Europe from a hardline, ideological position, notwithstanding that we lost our majority in the General Election, they are still banging on in that hardline, hard-Brexiteer way and it's not acceptable".

She said if she and the likes of Tory former chancellor Ken Clarke could compromise and accept Britain is leaving the EU, then the Brexiteers must compromise too.

She said: "They've got to drop the rhetoric and they've got to come and find a solution to this Brexit problem which is undoubtedly going to be a nightmare unless people compromise. "That is why I will no longer vote against my conscience - I am going to go through the lobby with [Lady Hermon] because it's the right thing to do."

Ms Soubry told the front bench it "doesn't help when we are told that we will be leaving the customs union, we will be leaving the single market, because we have to find a compromise".

"I think the Prime Minister moved towards that with this idea of regulatory alignment, makes a lot of sense, people are coming together, a consensus is forming - I think the consensus neatly lies with a customs union."

Tory former attorney general Dominic Grieve said any suggestion that leaving the EU involves "uncoupling Northern Ireland into a separate regulatory regime for the benefit of maintaining the Good Friday Agreement" is a "complete non-starter".

"Totally unacceptable to me, but I have to say I did not understand the Prime Minister's words and the agreement she reached as being indicative that she was intending to do any such thing," he said.

"If she was, all I can say is that she's not long going to survive the views of her own political party which as far as I can see are unanimous on this, irrespective of whether the members concerned were those who most enthusiastically embraced Brexit or most vigorously sought to prevent it."

Speaking on the Irish border issue, Mr Clarke described the Government's policy as "slightly ludicrous".

He said during his speech: "The Government keeps saying its committed to an open border, absolutely right consistent with the Good Friday Agreement, then says we're leaving the single market and we're leaving the customs union.

"I have said before, said it many times they are at complete contradiction it seemed to me completely incompatible. The two together are an oxymoron.

"I thought at last the light dawned when the Prime Minister moved in her discussion with the Taoiseach and reached an agreement.

"No doubt she believed she would get the approval of this House for regulatory convergence in certain areas at least across the border.

"I took that to mean the whole United Kingdom because we can't have separate arrangements in Ireland, so at last common sense is dawning, because whatever you call it you can't have any trade agreement with any other country in modern times unless actually you've agreed to mutually binding arrangements for regulatory and customs convergence."

Mr Clarke said he hoped the breakdown between the Government and the DUP over this agreement was down to "sheer incompetence".