The Archbishop of Canterbury, Justin Welby, said he would never have forgiven himself if he had not supported the Chief Rabbi’s dramatic warning about Jeremy Corbyn’s Labour Party in the run-up to the 2019 general election.

The Chief Rabbi had questioned the then Labour leader’s fitness for office as Prime Minister over the party’s handling of antisemitism allegations.

Recalling the events in a public conversation with Sir Ephraim Mirvis this week, Archbishop Welby said the Chief Rabbi had forewarned him that he had to speak out.

“I said immediately I will support you,” the Archbishop said.

When he had consulted his staff about his decision, he recalled, “Without hesitation, everybody around me said, ‘Good’.”

After the Chief Rabbi’s unprecedented intervention in the election campaign, Archbishop Welby released a statement to highlight “the deep sense of insecurity and fear felt by many British Jews”.

Sir Ephraim was loudly applauded by an audience at the JW3 centre in London on Tuesday when he observed “The Archbishop of Canterbury volunteered to issue his voice… There was an enormous amount of courage and we appreciated it enormously”.

To which the Archbishop responded, ”I think it would have been cowardice not to say something. It was so obviously right I knew I would never forgive myself if we didn’t speak clearly…I know my history…You have to cut off these things off straight away because if you don’t, they become overwhelming.”

The two spiritual leaders were taking part in an event held by the Yoni Jesner Foundation to mark the 20th anniversary of the death of the young Glaswegian, who was studying at yeshivah in Israel when he was murdered in a terror attack on a bus.

One of Yoni Jesner’s kidneys donated after his death was received by a Palestinian girl.

In a wide-ranging dialogue that spanned religious illiteracy in general society to the need for religious voices to be heard on issues such as climate change or artificial intelligence, what was evident was the warmth of the relationship between the two leaders.

“In the Archbishop of Canterbury we have one of our greatest friends, a friend of Jews and a friend of Judaism,” Sir Ephraim Mirvis.

In a good-humoured exchange of views, they revealed moments when they had encountered unexpected difficulties in saying what they wanted to say in public.

The Archbishop recalled being invited to give the Thought for the Day for BBC’s Radio 4 on Easter Friday.

“Naively, I assumed I should talk a bit about the crucifixion,” he said. Then “I got a call from the BBC where they said there’s a bit too much Jesus in this.”

“I’ve never been told that,” the Chief Rabbi chipped in.

Sir Ephraim said he had once had a script for a Radio Scotland talk rejected. It was shortly before the festival of Shavuot and a few months before the 2014 referendum on Scottish independence. “What I had written was the Israelites were leaving the yoke of their Egyptian bondage in search of an independent future,” Sir Ephraim said.