The earliest known map of Ireland without Britain – found in a 15th century atlas valued at up to €3 million – has failed to sell at auction in London. Dated from 1463, it was made in Venice by the cartographer Grazioso Benincasa.

It went under the hammer at Christie's in London on Wednesday afternoon, with an estimate of £1.5 million-£2.5 million where it "sparked widespread admiration and interest", according to the auction house but failed to find a buyer. Christie's said the "highly important and intriguing map" showing Ireland "aptly bordered in bright green" was the "oldest known separate, individual map of the island".

The atlas, owned by a private collector, was formerly in the art, antiques and rare books collection of the British Rail pension fund which was sold off in the 1980s when the state-owned transport company was privatised. Later in the auction of valuable manuscripts and printed books, a 17th century portfolio of watercolours of the natural world by German artist Johann Joachim Henneberger sold for £122,500.