A Stradivarius violin has set a new auction record after selling for £9.8m.

The "Lady Blunt" – named after its 19th-century owner Lady Anne Blunt, an Arabian horse breeder who was Lord Byron's granddaughter – was sold by the Nippon music foundation to raise money for Japan's tsunami relief fund.

It was bought by an unnamed bidder for four times the previous Stradivarius violin record. There are about 600 Stradivarius violins in the world but the only other in such pristine condition is the "Messiah" in the Ashmolean collection in Oxford.