The crowd erupted into cheers as the clock hit 11 p.m. (2300 GMT), the moment of Britain's exit. After a barrage of fireworks, smoke filled the area as onlookers hugged, popped champagne corks and filmed the moment on their phones.
"This is a fantastic day, a really really fantastic day.
It's been a long time coming," said Tony Williams, 53, from south-east London.
"We are free, from 11 o'clock, we have done it, and it is a great, great pleasure. We have done it." Brexit supporters young and old packed into Parliament Square to hear Brexit's other talisman, campaigner Nigel Farage, and revel in a mix of nostalgia, patriotism and defiance.