So who knows exactly what's up Lily Allen's nose?

Lily Allen has sworn off drugs - so eyebrows were raised when she seemed to have something suspicious up her nose after a party.

Party girl: Lily Allen leaving the celebrity bash

The singer was snapped leaving a bash hosted by PR mogul Matthew Freud in Notting Hill on Tuesday. In the photograph, she appeared to have something white up her left nostril.

Close-up: the white traces around Lily's left nostril

One onlooker said: "No one could work out what it was. Perhaps she was suffering with a cold." Lily's spokesman said today that she had not taken drugs.

And according to photographers, a camera flash can produce a white glow if the subject has a sniffly nose.

Allen, 24, has admitted dabbling in drugs. Earlier this year, she said she used to wake up and "there would have been empty vodka bottles everywhere, drugs, whatever.

"When all this happened I was 21. Becoming famous is all a bit scary and weird and I had no idea how to handle it.

"You go out and you get off your head. You get invited to parties and there's free drink and drugs. Well you do, don't you?"

Last December she said she had no intention of taking drugs "at the moment" - but added she could not say "never again".

The Freud party had a big celebrity turn-out, with Stephen Fry, David Walliams and Jemima Khan showing up.