Rishi Sunak should apologise for his transgender jibe which was made while Brianna Ghey's mother was in parliament, Gordon Brown has told Sky News.
The former PM was speaking to the Politics Hub With Sophy Ridge a day after the current occupier of Number 10 joked during Prime Minister's Questions about Sir Keir Starmer's record on gender recognition, while Esther Ghey was on the parliamentary estate.
Peter Spooner, the father of murdered transgender teenager Brianna, has also told Sky News he thinks Mr Sunak should say sorry for what he called the "degrading" and "dehumanising" remark made in the Commons on Wednesday.
Mr Sunak had accused Sir Keir of having difficulty in "defining a woman" during an attack on Labour Party U-turns. The PM has refused to apologise and said his comment had been "absolutely legitimate".
Mr Brown has had his own moments of regret - including calling a voter he had just met a "bigot" after a discussion on immigration.
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He later returned to the woman's house to apologise - telling waiting journalists that he was a "penitent sinner".
Mr Brown told Sophy Ridge: "Prime ministers make mistakes. I don't think you can say that every prime minister will fail to make some mistakes, but I think you should apologise if you get things wrong.
"And I mean it is a very sad and really tragic, tragic case of a family in grief.
"I know, he's said he's compassionate about the family, but perhaps he should do what I had to do on one or two occasions and apologise. And I do accept that if you make mistakes, you've got to correct them quickly."
Speaking on a wide range of topics, Mr Brown stated that a second Donald Trump presidency would "cause a lot of damage to jobs in Britain".
The New Labour titan said European countries should warn the US about the dangers the world would face if Mr Trump returns to the White House.
"I would normally say British leaders should keep out of American politics, and they would say any American leader should keep out of British politics," he said - but "we've got to sound some worry".
Mr Brown added: "If Donald Trump were elected, he's promised a 10% tariff on goods. So you've immediately got a trade war."
And this trade war would "actually cause a lot of damage to jobs in Britain".
Mr Brown, who was the UK's chancellor for a decade, said that this year is different to 2016 in that Mr Trump actually has policies to scrutinise - including leaving the World Bank, the International Monetary Fund, and potentially withdrawing support for Ukraine.
This - and uncertainty about his policies in China and the Middle East - "are huge issues not just for America, but for the whole of the world - and particularly issues for Britain, and Europe as well", according to Mr Brown.
He added: "I think in this instance, we've got to speak out and say, look, we are worried about what the policies that he's proposing are."
Mr Brown, who left parliament in 2015 having been ejected from Number 10 in 2010, now campaigns on child poverty in the UK.
He told Sophy Ridge that there is an "emergency" and a "crisis" at the moment with regard to young people and the cost of living.
A combination of factors, including the ending of support payments for energy, inflation, the two-child benefits cap and other matters have left families unable to afford basics like toothpaste, soap, shampoo and winter coats.
He highlighted examples of schools which have set up washing machines to ensure students have clean clothes.
"And so you've got a cleanliness problem, you've got a health problem, and something has got to be done to make life better because we are sacrificing the future of thousands of children on the altar of failing to take into account that we've got to do more about that poverty," he said.
Mr Brown backed Sir Keir Starmer's plan to look at reforming Universal Credit - and highlighted his continuing disapproval for the two-child benefit limit.
This refers to the policy of restricting means-tested financial support to families with three or more children.
He stopped short of calling on Sir Keir to scrap it, but said he never liked it and said reviewing Universal Credit is the "right thing".
Labour has not said if it would scrap the policy.
On Labour's U-turn on green policies, Mr Brown revealed he had not been asked by the current party leadership for his advice.
He noted that he did not want to be a "backseat driver" or to "pontificate from the outside" - but added that "the situation has changed and "we are in a new fiscal cycle".
The former chancellor said: "Our economy is not growing.
"I mean the best we can hope is we get to 1% over the next year and that will not be enough to keep standards of living rising or alternatively to pay for our public services.
"So these are difficult decisions that Keir Starmer, [shadow chancellor] Rachel Reeves have got to make.
"If they asked for my private advice, I said I'll give it."