An estimated 26,500 people are due to take part in the parade and there is expected to be up to one million people in attendance at the festival, which promotes rights for the lesbian, gay, bisexual and transgender (LGBT+) community.

London’s annual march is the biggest Pride celebration in the UK and now in its 45th year. This year’s celebration marks 50 years since homosexuality was decriminalised in England and Wales.

As part of the annual Pride weekend, a rainbow flag has been projected on to the Palace of Westminster for the first time.

‘We want Pride to be a friendly and safe event for everyone to enjoy and, to help us, we need the public to take the usual precautions by remaining vigilant and reporting anything of concern to police officers or stewards at the event.’

The parade comes after what is believed to be the world’s largest Pride festival, with more 100 events since Saturday June 24.

Since its inception in 2000, WorldPride Madrid 2017 is held once every several years in major cities across the world – this year it was held in Madrid to coincide with the 40th anniversary of the first LGBT pride protest in Spain.

In a closing ceremony in central Madrid on Sunday, revellers gathered to see musical acts from across the world, including the host cities of previous parades, Jerusalem, Toronto and London.

The next World Pride will take place in New York in 2019, coinciding with the 50th anniversary of the Stonewall demonstrations, when members of the gay community protested against violent treatment at the hands of the police.

The first official Pride march in 1972 saw 2,000 people take part. Last year’s event in London saw more than 40,000 people join in to march in front of a crowd of nearly one million.

Pride parades and festivals are taking place across the UK and the world on Saturday, including in Bristol Pride Day 2017 and Pride Barcelona.