London Mayor Boris Johnson has explained how he was “hit very hard” by his tour of Yad Vashem today, during which he appeared visibly distressed at several points.

The mayor, who focused many of his questions during the tour on the ability of Holocaust deniers to paper over the evidence to which he was exposed, said: “It is an incredibly emotional experience…. There are many moments in the tour when quite naturally you find yourself starting to weep; it’s a very, very powerful thing. But it is also a very powerful historical resource with the names of the victims and all the evidence… Never underestimate the ability of people to forget or distort the record for political ends.”

Mr Johnson signed Yad Vashem’s Guest Book with a note saying that “one must never forget the truth of what happened”. While exiting the museum, he added that the light of Jerusalem serves as redemption.

Boris Johnson, Yad Vashem. @MayorofLondon@ukinisrael#borisinisraelpic.twitter.com/gDnf3PNKnk

— Noga Tarnopolsky (@NTarnopolsky) November 10, 2015

“If you look at the sweep of the years that it covers,” he said, back at the King David Hotel, over a cup of coffee, “from beginnings of Zionism to the end of 19th century to the great post-war struggle, not least with Britain, it makes an unanswerable case for a Jewish homeland.”

Mr Johnson denied any political aspect to his trip, which was billed as a trade mission that aimed to nurture and grow the £5bn in annual trade between Israel and the UK.

“David Cameron is doing a terrific job and there’s a queue of several people beyond him. The reason for coming here is technology and links betweeen the great start-up nations. We think that Israel will think about Britain as the scale-up nation, with lots of markets, financiers, people who understand commercial things in the big market. London really is good at that sort of thing.”

Lord Polak, who led Conservative Friends of Israel from 1989 to 2015, took a longer view. “Boris being here right now as the Mayor of the City of London, in the political cabinet, one of the key people in Conservative Party [is vital]. He is being updated about is going on here, having a look around Israel at the time of the rise of Daesh. It is so important that he maintains ties to [Israeli] ministers, these relationships are vital going forward. He’s a player and he’ll be around for a long time.”

Mr Johnson said he was in Tel Aviv and Jerusalem “looking for Israeli investment”. This, he said, was itself “a tribute to Israel,” adding that Israel is the second largest foreign state represented on the LSE. “It also shows their wisdom-- it’s the place to raise finance,” he said.

The rest of his day will be devoted to cheerier subjects, including a visit to the Maheneh Yehuda market and a cooking session with top Israel chef Assaf Granit, the owner of London’s Palomar restaurant, which Mr Johnson said he was embarrassed not yet to have visited. “Londoners are on the whole incredibly welcoming of talented people from abroad,” he said, referring to Palomar’s numerous prizes and laudatory reviews.

Following his stint in the kitchen, he is expected to play football with Israel’s exuberant President Reuven Rivlin and a group of Jewish and Muslim boys, and end his second day in Israel with a speech on Winston Churchill at the Konrad Adenauer Forum.

Mr Johnson is scheduled to spend a brief few hours of his last day in the West Bank and in a meeting with the Palestinian prime minister, Rami Hamdallah.

“The reality is that we do need a two-state solution. I want to reemphasise the point I made about the two halves of that declaration. Winston Churchill came here in 1922 and had to consider how to give effect to that declaration.”

Asked whether he believes the Israeli government shares his view about the two-state solution, Mr Johnson said “I hope they do.”