This portrait of William Shakespeare, painted in 1610, is believed to be the only surviving picture of William Shakespeare painted in his lifetime. (Photo credit should read Leon Neal/AFP/Getty Images)

William Shakespeare scholars in Britain have unveiled what they say is the only true image of the Bard that was created during his lifetime.

"We're 90 per cent sure that it's Shakespeare," said Paul Edmondson of the Shakespeare Birthplace Trust.

"You'll never be entirely certain. There will always be voices of dissent."

Trust officials say the painting was likely used for the famous engraving of Shakespeare that graces the cover his First Folio collection of plays.

Edmondson says all other images were made after the playwright's death in 1616.

"We think it was painted in 1610 and several copies of it were made early on, including the engraving. So our portrait is the primary version of one of the greatest portraits of Shakespeare."

Subjected to infrared imaging

Edmondson also says the portrait was used as a basis for another well-known portrait of the writer that hangs in the Folger Shakespeare Library in Washington.

He said scholars are convinced it is Shakespeare because so many copies of the painting were made as well as the fact it was handed down through the generations along with a portrait of the Earl of Southampton, Shakespeare's main patron.

Researchers carefully checked the history of the painting as well as subjecting it to infrared imaging and also dating the oak panelling.

The portrait had long been part of the Cobbe collection owned by the Cobbe family, but had not been connected to Shakespeare until 2006. That's when one of the family members saw the Folger Shakespeare painting on display at a travelling exhibition in London and connected the two.

The Cobbe Shakespeare will be on exhibit at the Shakespeare Birthplace Trust in Stratford-on-Avon from April 23 until Sept. 6.

Canadian portrait may also be authentic

That doesn't end the Shakespeare portrait mystery.

There is another painting in Canada said to have been painted during Shakespeare's life.

Owned by Ottawa resident Lloyd Sullivan, the painting — known as the Sanders portrait — is reportedly that of the Bard at 39.

It has gone on display many times and tests indicate it was produced at the right time to be legitimate — if the man in the picture is Shakespeare.

The portrait announcement comes on the same day the Museum of London proclaimed that the foundations of the theatre where Shakespeare's plays were performed had been found in Hackney on the eastern outskirts of London.

It was called The Theatre and built in 1576 by James Burbage.

Archeologists had also found a piece of pottery with an image of a man who resembles Shakespeare, said Museum of London spokesman Tim Morley.

An abandoned warehouse now sits on the site where experts believe Romeo and Juliet was performed.

Officials plan to build a small new theatre on the site.

With files from the Associated Press