A LOST masterpiece by one of the world's greatest artists looks about to be lost to Britain for good.

A Government-imposed temporary export ban on the Michelangelo drawing, A Study of a Mourning Woman, has expired after two months.

Because no British buyer came forward, it is expected to be delivered to an American collector.

The drawing was discovered at Castle Howard, North Yorkshire, pasted in an album of drawings in the library, and was sold at auction in the summer of 2001 for almost £6m.

It was bought by a fine art dealer, and it is believed the American collector has offered in the region of £7.5m for the work.

The Government imposed the temporary export ban in November.

A request by the National Gallery of Scotland for £4.1m towards the purchase was rejected by the Heritage Lottery Fund.

The drawing was found among otherwise undistinguished artworks and is regarded as a rare example of Michelangelo's earlier work.

The artist is probably best-known for painting the ceiling of the Sistine Chapel and only a handful of drawings by him are known to exist.

The drawing is comparable to others he did dating back to 1490, of which only one is held in this country.

Experts say it is pivotal because it shows elements of his sculptural cross-hatching style but also the later white "heightening" he used to highlight his drawings.

The drawing remained unrecognised for more than 250 years after it was bought at a London auction by Henry Howard, the 4th Earl of Carlisle, in 1747.

It was rediscovered in the late 1990s by an expert who was updating Castle Howard's art inventory.