NK Guy sez, "Every year dozens of clowns gather in a London church to celebrate the life of Joey Grimaldi, the father of modern clowndom, who died in 1837. They also mourn the passing of any fellow clowns who may have died that year."
I used to have an office around the corner from Exmouth Market, Grimaldi's former home, and I loved to stop and admire his blue disc (alas, my landlords went batshit and I had to move; luckily I found new digs right under the marvellous London Hackpspace).
Born of an Italian father and an English mother in 1778, Grimaldi lived and worked in the world of London theatre. His talent for physical comedy made him a massive superstar of his age, though Grimaldi's life fell into a predictable pattern of tragedy, and he died broken and crippled in Islington, age 58.
Since the war, British clowns have been holding a special memorial service each February to celebrate the life of this founder of British clowndom. And since the 60s Holy Trinity Church in Hackney has permitted them to attend in full clown regalia. The event is organised by the Clowns International group, who also maintain a small clown museum in Wookey Hole.