I suppose it could be said to date back to the time of the Prince Regent, later King George IV, some 200 years ago. He it was who had what was pretty much a bog standard farmhouse enlarged and converted in the Royal Pavilion we see today - seemingly Indian-inspired architecture decorated internally in the Chinese style.
A friend once told me how he was sitting in a pub in central Brighton, idly gazing out of the window, when he saw a man dressed as a pirate, complete with a stuffed parrot on his shoulder, come round the corner of the street, put his skateboard on the ground, and skate off. That man was 60 if he was a day - but nobody batted an eyelid.
Brighton is also thought to be the only place where a block of council flats has a blue plaque. The city of Brighton and Hove awarded Doreen Valiente a blue plaque to commemorate her life and honour her achievements. The plaque is the first in the world awarded to a witch. According to the Doreen Valiente Foundation web site, "Doreen Valiente remains, simply, the most influential woman in the world of modern Witchcraft".
Possibly the city's best-known eccentric today is Disco Pete. In his mid-70s, Pete will bne seen anywhere in the city where there is open-air music - as here on the lower promenade, although he is usually dressed much more colourfully.