Oct. 25 (Bloomberg) -- Banksy's defaced banknotes, carrying Princess Diana's face instead of Queen Elizabeth II's, tripled their top estimate at a Bonhams sale in London yesterday, as demand continued for works by the graffiti artist.

Banksy's ``Di Faced Tenners,'' a 2004 screenprint of modified 10-pound notes, sold for 24,000 pounds ($49,000) with commission, compared with a top estimate of 7,000 pounds pre-commission, Bonhams said in a statement. Five other Banksy works doubled or nearly doubled their top estimates, including ``Untitled, Rat and Sword,'' a critique of the British legal system.

Banksy, born in Bristol, England, in 1975, keeps his real name a secret. He rose from the U.K. streets to the auction rooms in 2004, and has drawn collectors from hedge funds to artist Damien Hirst.

``As prices rise, new collectors come in,'' said London dealer Steve Lazarides, who represents Banksy, at a Sotheby's auction on Oct. 15.

Bonhams sale of 11 Banksys yesterday was part of 51 images on the market this month, at Sotheby's, Bonhams, Bloomsbury Auctions and a gay bar in London, valued at as much as 1.1 million pounds before commissions. Many of the works have sold near or above their top estimates.

To contact the reporter on this story: Linda Sandler in London at lsandler@bloomberg.net.

Last Updated: October 25, 2007 02:53 EDT