LONDON A 12th-century iron key to the Ka’ba in Mecca, the holiest site in Islam, was sold for £9.2 million at Sotheby’s in London yesterday. Its existence was previously unknown and prompted a bidding battle that took the price to more than 18 times the £400,000-£500,000 estimate in an auction of Islamic art, whose 405 lots sold for a total of £21.5 million. The key, which is 37cms (15in) long, was formerly in a private collection in the Lebanon and dated from 1179-1180. It was bought anonymously and is the second-earliest of only 58 known examples. Others are in European and Middle Eastern museums. The key was the ultimate symbol of religious power. It was engraved: “This is what was made for the servant of . . . God during the time of our lord the Iman, son of the Iman al-Muqtadi Abu Ja’far al Mustansir Abu’l-Abbas 575â€. The rarity was the highlight of a week of Islamic sales in London. Christie’s also took £11.8 million in an auction on Tuesday. A leaf from a 7th-century copy of the Koran on vellum, probably from Medina, took £2.4 million against an estimate of £100,000-£150,000, setting a new world auction record for any Islamic manuscript.