Is this the face of teenage queen Lady Jane Grey?

The portrait was long-believed to be that of Lady Jane Grey, but after 300 years its attribution was rejected

Experts believe they have uncovered enough evidence to suggest a Tudor-era portrait could be the only known image of Lady Jane Grey painted in her lifetime.

She was "the nine days queen", whose brief reign was an unsuccessful bid by Protestants to prevent the accession of her Catholic cousin Mary I (1553 to 1558).

Executed aged just 17, if the image is of her, it was changed over the centuries to depict her as a "subdued, Protestant" martyr. The painting is on loan to Wrest Park, Silsoe, Bedfordshire, its previous home.

"While we can't confirm this is definitely Lady Jane Grey, our results certainly make a compelling argument," said Rachel Turnbull, of English Heritage.

New research shows significant changes were made to the original portrait, especially to the sleeves, and the scarf on the shoulders is probably a later addition

English Heritage worked alongside the Courtauld Institute of Art and dendrochronologist Ian Tyers to discover "evidence of a once perhaps more elaborate costume", the senior collections conservator said.

"It is possible that we are looking at the shadows of a once more royal portrait of Lady Jane Grey, toned down into subdued, Protestant martyrdom after her death," she added.

Who was Lady Jane Grey?

At some point the portrait's eyes, mouth and ears were scratched out - a National Portrait Gallery image of Lady Jane bears the same marks, said English Heritage

• Born at Bradgate Park, Leicestershire, in about 1537, she was Henry VIII's great-niece

• Her high-status family made sure she received as good an education as the king's daughters, learning Greek, Latin, Hebrew, French and Italian

• Protestant King Edward VI (1547-1553) hoped to make her queen after his death instead of his Roman Catholic sister Mary

• She was proclaimed queen on his death by her father-in-law the Duke of Northumberland, but her reign only lasted from 10 July to 19 July 1553

• She was executed at the Tower of London in the wake of a Protestant uprising against Mary in 1554

Source: Historic Royal Palaces

All known portraits of the teenager were painted after her death.

The most famous is probably The Execution of Lady Jane Grey, painted in 1822 by Paul Delaroche.

In it, she is helpless and blindfolded in front of the executioner's block.

She was seen as a Protestant martyr in the centuries after her death, having refused to convert to Catholicism to save her life, according to Historic Royal Palaces

Historical novelist and historian Philippa Gregory, who saw the portrait at English Heritage's conservation studio, said: "Certainly, the features are similar to those of her portrait at the National Portrait Gallery.

"This is such an interesting picture posing so many questions, and if this is Jane Grey, a valuable addition to the portraiture of this young heroine, as a woman of character – a powerful challenge to the traditional representation of her as a blindfolded victim."

What is the newly revealed evidence?

A range of experts used the latest scientific techniques to uncover the painting's secrets

• Infra-red reflectography shows significant changes to the sitter's costume after the portrait was completed, including to her sleeves and coif - the linen cap worn over her hair

• Her eyes, mouth and ears were deliberately scratched out, probably an iconoclastic attack in which the image was destroyed for religious or political reasons

• Dendrochronological analysis (tree ring dating) of the painted panel suggests it was used between 1539 and 1571. It was made from Baltic oak boards

• The back of the panel displays a merchant or cargo mark identical to one used on a royal portrait of Edward VI

"Regardless of her identity, the results of our research have been fascinating," said Rachel Turnbull (above with the portrait)

The painting was acquired by one of Wrest Park's former owners in 1701 as an image of Lady Jane Grey.

"It remained the defining image of the 'nine days queen' for more than 300 years, until its attribution was thrown into doubt and its identity rejected," said Peter Moore, the stately home's curator.

It is on loan from a private collection, alongside six other paintings with a connection to the house and its former owners.

"It is thrilling to have this painting back at Wrest and the new research provides tantalising evidence which brings us much closer to the assertion that this could be Lady Jane Grey," he added.