There were ill-tempered scenes in parliament on Wednesday as Boris Johnson was told to withdraw remarks about Keir Starmer – after appearing to try and link the opposition leader to the IRA.
The prime minister had accused Sir Keir of being "a leader of the opposition who supported an IRA-condoning politician who wanted to get out of Nato", an apparent reference to former leader Jeremy Corbyn.
Sir Keir reacted angrily to the attack, demanding the prime minister withdraw his comment – an intervention which was also backed by the Commons Speaker Lindsay Hoyle.
The opposition leader said he would not be "lectured" by the prime minister and that he had worked in Northern Ireland with the security services prosecuting dissident republicans.
Immediately after making his comments Mr Johnson was interrupted by Mr Hoyle, who told him: "I think there are questions being asked, we do need to try and answer the questions put to the prime minister, it would be helpful to those watching to know the answers."
The prime minister appeared to try and continue with his attack, telling the Commons: "I think it would be helpful for all those who are watching to know..." before being interrupted again by the Speaker, who told him "I make the decisions."
Returning to the subject later in the session, Sir Keir angrily retorted: "The prime minister said something about the IRA and I wanted to take it back. I worked in Northern Ireland for five years with the police service of Northern Ireland bringing peace – prosecuted, as the director of public prosecutions, serious terrorists, for five years, working with the intelligence and security forces and police in Northern Ireland. I would ask the prime minister to have the decency to withdraw that comment."
After the prime minister ignored the plea, the Speaker Mr Hoyle intervened again, stating: "Can I just say there was a question about the allegation on Northern Ireland ... I think in fairness that he would like to withdraw it?"
But the prime minister said: "I listened to the protestations of the right honourable gentleman... I think they would have been more in order throughout the long years during which he supported a leader of the Labour party..." before being cut off again by the Speaker.
Sir Keir said: "When the prime minister has worked with security and intelligence forces prosecuting criminals and terrorists he can lecture me. I asked him to do the decent thing but doing the decent thing and the prime minister don't go together."
Jeremy Corbyn's views on Northern Ireland were the subject of controversy during his leadership. Mr Corbyn has long supported a United Ireland, though he has repeatedly condemned violence, and voted in favour of the Good Friday Agreement.
As an MP Mr Corbyn met with Sinn Fein representatives at the height of the Troubles, which was controversial. He also campaigned on behalf of people wrongfully convicted of terrorism offences, such as the Guildford Four and the Birmingham Six, who later had their convictions overturned.
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