Mayor says London's pride parade 'best antidote' to tragedy

London's mayor has called the Pride in London parade the biggest ever and says the celebration provides the "best antidote" to recent tragedies.

Sadiq Khan on Saturday told revelers at the gay pride event that the festivities provided welcome relief from recent bouts with terrorism.

The annual parade honored members of the emergency services who were praised for heroic work responding to extremist attacks and the Grenfell Tower fire.

More than 25,000 people took part in the gala parade, with up to 1 million people watching in central London.

The huge crowd included many representing countries where homosexual acts are still criminalized.

As part of the festivities, a rainbow flag is to be projected onto the Houses of Parliament for the first time.