In pictures: Pride in London through the years
As thousands of people prepare to join this year's Pride parade through central London, BBC News takes a look at some of the most striking images from the event's 45-year history.
The first official UK Gay Pride Rally was held in London on 1 July 1972. The date was chosen as it was the nearest Saturday to the anniversary of the Stonewall riots of 1969, which saw people protest against a police raid at the Stonewall Inn, a gay bar in Manhattan.
In 1976, a picnic was held in Victoria Gardens by the Houses of Parliament during what was then called Gay Pride Week.
In 1981 the Pride March was moved to Huddersfield for one year only, in support of the Gemini Club, which police had once called "a cesspit of filth".
In 1983 the march was renamed Lesbian and Gay Pride and in the 1990s became more of a carnival event.
Pride London was formed in 2004. Since then, a political rally has been held in Trafalgar Square straight after the parade.
The march in 1996 saw gay men make a statement about religious attitudes to homosexuality by impersonating the Pope and members of the Mafia.
This year's parade is set to be the biggest yet, with more than 300 groups marching and more floats taking to London's streets than ever before. There will also be for the first time a seated grandstand - tickets for which have already sold out.
The 2017 theme is Love Happens Here - and marks 50 years since homosexuality was decriminalised in the UK.
Pride in London has issued advice for those planning to attend: "We recommend you come ready for a day of exciting parade watching.
"Bring snacks, refreshments, suntan lotion, sunglasses, a raincoat, and glitter".
The parade starts at 13:00 BST and takes a 1.4-mile (2.3km) route from just north of Oxford Circus on Regent Street, down Regent Street and through Piccadilly Circus.
It then heads down Pall Mall towards Trafalgar Square, and finishes in Whitehall at around 16:30 BST.
If you miss it on Saturday, or haven't had enough Pride, there's an event on Sunday in Vauxhall - Pride in the Park, which is run in conjunction with UK Black Pride.
All photographs subject to copyright.