Anyone who is over the whole Duchess of Cambridge thing might want to direct their attention to a different kind of royalty. Princess Julia – DJ, writer, general face of London subculture – is nightlife royalty, and a stalwart of the capital's fashion scene. Now five years of her exploits have been captured in What Would Julia Do, a book compiled by photographer Rebecca Thomas. It shows her subject palling around with designers Louise Grey, Jonathan Saunders and James Long; doing the tango with much-respected Style.com critic Tim Blanks; and saying hello to Boy George. Put it this way: she knows anyone who is anyone in London fashion, and has inspired most of them.

Julia herself puts this relationship down to mutual attraction. "I have always gravitated towards people who are creative and they have gravitated to me," she says. This may be to do with her quite extraordinary look, one that involves flawless makeup, bouffant hair, socks and glitter heels, whatever time of day. "I always feel like dressing up," she says. "Wearing something you love makes you feel happy and ready to face the world." Current favourites include a Lulu & Co pale denim skirt and straw boater.

Now in her early 50s, Julia's refusal to stop wearing exactly what she wants is a subtly subversive statement, and one that is inspirational for the next generation of modern bohemians. "I was really inspired by Julia's style," says Thomas. "It's a mix of classic Hollywood glamour, club culture and cutting-edge London designers."

Blipping on to the cult radar as a teenager in the late 70s, as one of the so-called Blitz kids, Julia – who first became a "Princess" in the early 80s – has been in the mix of London club culture ever since. She has been documented by Wolfgang Tillmans, appeared on the cover of magazines and starred in the video for Fade to Grey. "I'm very much a Londoner and I have been part of the scene for decades," says the fashion muse, who is namechecked by Jonathan Saunders in the latest issue of iD. "You have to own your own look – that's what I have done, but it's quite by accident." As Thomas's book shows, it's a very happy one.

• What Would Julia Do is out today and available from the ICA Bookshop.