The Mayor of London, Boris Johnson, praised the organisers of this weekend’s Pride in London festival on Tuesday evening, and also made a risqué joke about gay men taking their husbands up the “Arcelor” on their wedding day.

Speaking last night at a £250 a head Pride gala dinner at Claridge’s, in Mayfair, central London, Mr Johnson said: “I’m here to tell you tonight at what I think is the most sensational Pride event I’ve ever seen” [interrupted by applause] “I want to congratulate all of the organisers for what you are doing , everyone for turning up”.

In a speech largely dedicated to the legacy of last year’s Olympics and Paralympics Games, Mr Johnson said: “People saw a city that was welcoming, and generous, and dynamic, and multicultural, and polymorphous and incorrigibly happy.”

He added: “It was an immense and unexpected surge of pride in a city where I think we judge each other and love each other not according to our race or gender or back background or any of that kind of stuff but according to what we have to offer. And I think we need to remember that emotion [and] feeling we all got in the summer of 2012.”

In the middle of his speech, Mr Johnson cited human rights campaigner Peter Tatchell as a key person who encouraged him to support equal marriage.

“Boris’s backing for same-sex marriage was a game-changer,” Mr Tatchell told the Standard in February of this year.

In 2010, Mr Johnson became one of the first senior Conservatives to back equal marriage, telling PinkNews.co.uk: “If the Conservatives and Liberals [Liberal Democrats] can get together in a national coalition and settle their differences, I don’t see why you can’t have gay marriage.”

Mentioning that “gay men and women in this city” will be able to get married by the autumn, once the Marriage (Same Sex Couples) Bill is signed into law, Mr Johnson jokingly suggested in his speech that they should get married at “the absolutely beautiful ArcelorMittal Orbit.”

He then added to much laughter: “It will be the perfect ceremony, you can take your partner up the …[Arcelor]. I think I can get away with that.”

Many including PinkNews and the Labour MP Angela Eagle misheard the Mayor’s joke, thinking he said amid much laughter “up the Arsenal”, a joke with the same meaning. Ms Eagle, the Shadow Leader of the House of Commons who was at the event, tweeted: “Boris speaking at LGBT Pride fundraising event made a speech about the Olympics & an off colour ‘joke’ about Arsenal #notamused #WontSayGay.”

The ArcelorMittal Orbit, the structure that towers over the London 2012 Olympics Park will reopen this autumn and will be licensed for weddings and civil partnerships.

Mr Johnson then concluded by commenting on why so many French people were attracted to living in London, and joked that he was now the mayor of France’s “sixth largest city.” He added that the Mayor of Bordeaux, Alain Juppé had previously served as prime minister.

Last summer, Boris Johnson released an Out4Marriage video, saying that he saw “no reason” why the “happy state” of marriage should be denied to “anybody”.