The Mayor of London will have the backing of his party leader when he makes his debut at Pride London on July 5th.

Boris Johnson is due to take part in the parade on the lead float.

He will also make a speech to the assembled crowd in Trafalgar Square.

Mr Johnson previously revealed that it will be his first ever Pride event.

Among the speakers at Pride London on July 5th will be Harriet Harman, Deputy Leader of the Labour Party and Secretary of State for Equality, and the Lib Dem leader Nick Clegg.

Last night Conservative leader David Cameron told PinkNews.co.uk that he is delighted that Boris will be taking part in the event.

“He will outshine you all!” he joked.

Mr Cameron was attending the launch of Root and Branch: Education for a Greener Future, a document examining the place of the environment in schools.

Written by Gregory Barker, Shadow Minister for the Environment and a close ally of the Tory leader, it advocates a new sense of “understanding and ambition in caring for our climate, biodiversity and landscape amongst Britain’s young people.”

Mr Barker was named as one of the most influential gay people in British politics by PinkNews.co.uk last December.

He has been a high-profile environmental campaigner within the Tory party and accompanied Mr Cameron on his much-publicised trip to the Arctic just after he became leader.

Critics have accused the Conservative leader of abandoning his “green” stance in the face of worsening economic conditions, but at last night’s launch he claimed his party had started a new political movement.

“If you look at what other centre-right leaders are doing, we have actually started something very important,” he said.

“It comes entirely naturally to Conservatives, because if you think about it, we believe in passing things on to future generations.

“What is there that is more important to pass on than a green and clean environment?

“I think the big argument we need to have with the British public and the media in the run up to the next election is basically this: if you believe in progressive goals, whether it is tackling poverty, unblocking social mobility or whether it is promoting a green environment, you need to use Conservative means in order to achieve them.

“Using markets, using prices, encouraging individual, personal and corporate responsibility.

“What excites me is not that we have got a big lead in the opinion polls, though of course that does excite me slightly, not just that we have done well in local elections, though that obviously excites me too.

“I think we have got a really big argument, a really big discussion to have with people, that if you want this sort of change in Britain, it is the Conservatives now who are setting the agenda, who have the great ideas, and it is the Conservative means to achieve the progressive goals that I am so enthusiastic about bringing forward.”

Root to Branch advocates training for teachers to encourage more school field trips, more university courses focusing on environmental affairs, stringent energy and water efficiency schemes for school buildings and a range of measures aimed at reducing waste and encouraging energy saving in schools.