Sammy Wilson MP has said Boris Johnson's father Stanley is a loose cannon and a nonentity after he claimed Margaret Thatcher would have fixed the Irish border Brexit dilemma by saying "if the Irish want to shoot each other, they will shoot each other".
Mr Johnson Sr, whose former foreign secretary son Boris last month claimed that Theresa May's Brexit strategy had put the UK "in a suicide vest" and handed the detonator to Brussels, made the statement on the ITV show Good Morning Britain yesterday.
In an interview with hosts Piers Morgan and Susanna Reid, he said that former Prime Minister Margaret Thatcher would have found the focus on the Irish border in the Brexit negotiations to be unacceptable.
He said: "She would have said it is quite intolerable that this whole question of a Northern Ireland border has come to dominate a decision about the future of our country."
When asked how Mrs Thatcher would have fixed the issue, he continued: "She would have said, 'Look, if the Irish want to shoot each other they will shoot each other whether there is a hard border or whether there is a soft border, that is something the Irish will do if they want to do it'.
"So I think basically Mrs Thatcher would not have had any truck with this scheme by the EU to elevate the border question into a way of making sure we stay in the EU."
DUP Brexit spokesperson Sammy Wilson slammed Mr Johnson Sr as a "nonentity" and accused him of making "flippant" comments which "could be considered quite hurtful to Troubles victims' families".
He added: "It doesn't surprise me - he's a loose cannon.
"It's not Margaret Thatcher, it's Theresa May who is making these decisions and she has to make a decision in the context of needing our support, and we will hold her to her promises.
"Stanley Johnson's remarks could be considered quite hurtful for Troubles victims' families.
"I think it is a rather flippant way of describing what has been a very, very difficult situation in Northern Ireland, which has been subject to 30 years of terrorism."
Labelling Mr Johnson Sr "irresponsible", Mr Wilson claimed that EU chief negotiator Michel Barnier and Taoiseach Leo Varadkar had been "equally insensitive regarding the sensitivities of unionists around the border and sovereignty issues".
"I don't think Mr Johnson Sr is any less insensitive than the EU side of the negotiations have been," he said. "Interventions by a nonentity are less important than interventions by people who have a role in making choices and who can influence the outcome."
Mr Wilson added that he and his party were not expecting to hear any more from the Prime Minister or from the Brexit negotiations for the rest of this week.
SDLP policing and justice spokesperson Dolores Kelly called on Mr Johnson Sr to withdraw his comments, which she branded "insulting and offensive".
She said: "One wonders if this is well thought out or designed to court controversy and keep him in the limelight.
"The contribution this makes could not be described as helpful, and it is almost making a joke out of what happened here.
"To be so flippant and say this in the context that he has is quite insulting and offensive."
Mrs Kelly said that Mr Johnson Sr should have been "a lot more respectful".
"Any informed person knows that the Northern Ireland Office has just completed an extensive consultation on the legacy of the past, which is something that we are still finding very challenging 20 years on from the Good Friday Agreement," she continued.
"Over 3,500 people lost their lives in the Troubles - a huge number for such a small area.
"He should be a lot more respectful and aware of how the words he uses can cause offence."
Mrs Kelly called for Mr Johnson Sr to withdraw his "absolutely nonsensical comments".
She added: "I would call for him to withdraw the remarks - they are offensive, hurtful and insulting."