A PORTRAIT claimed to be the only known picture of William Shakespeare to be painted during the Bard’s lifetime looks like having only a fleeting moment of fame.

For it appears to be a copy of a portrait in Oxford’s Bodleian Library of an altogether less famous Elizabethan figure, Sir Thomas Overbury.

The painting believed to be of the Bard has hung on the walls of the Cobbe family for about 300 years. At the weekend it was featured on the front page of the Sunday Times, with the claim that it is an authentic image of Shakespeare, a claim apparently supported by the foremost expert on Shakespeare, Stanley Wells, the general editor of the Oxford Shakespeare series.

But some clever detective work by Oxford academic Katherine Duncan-Jones has revealed that the portrait in fact bears a striking likeness to a picture of Sir Thomas, a dashing nobleman who came to a violent end in the Tower of London.

The news will disappoint millions who had hoped that our greatest poet was the handsome rosy-cheeked figure in what is known as the Cobbe portrait.

The painting’s subject certainly cuts an altogether more romantic figure than the familiar round-headed, bald man seen on the First Folio of Shakespeare’s collected works.

Prof Duncan-Jones, who has written a biography of Shakespeare and edited his sonnets, said she became suspicious on being told that the portrait that appeard on the front of the Sunday Times was painted in 1610.

She said: “He looks much too young. Shakespeare would have been 46. The figure in the painting also doesn’t look like an actor — he is far too grand. Shakespeare was not a nobleman.”

Tarnya Cooper, a 16th-century curator at the National Portrait Gallery, also said she was sceptical. When Ms Cooper suggested the portrait might represent Sir Thomas Overbury, the Oxford author got to work hunting out the portrait of the courtier that she had remembered seeing in the Bodleian long before.

Prof Duncan-Jones said: “It was once kept on public display. But it is now kept a few floors down in an air-conditioned basement.”

She set out the story of her investigation in an article that appears in this week’s Times Literary Supplement.

The piece will certainly make uncomfortable reading for those convinced the only authentic image of Shakespeare had at last been found.

The Shakespeare Birthplace Trust had unveiled the ‘Shakespeare’ picture at the Mayfair base of the English Speaking Union in London. The trust’s director had called it “a momentous historical and fascinating event”.

The portrait is also expected to go on display at Shakespeare’s birthplace in Stratford. It has been in the possession of the Cobbe family since the early 18th century and kept initially at a property in Hampshire before being moved to a house in Surrey run by the National Trust.