A leading Tudor historian has made an important discovery in an unlikely place – eBay.

Alison Weir believes that a 19th-century engraving on the internet shopping site could be a 'lost' 16th-century portrait of Anne Boleyn, Queen of England.

The sitter's lavish necklace bears the initials of Anne Boleyn Regina, Henry VIII's tragic second wife. Her ornate head-dress is embroidered with 'As' and her 'A' pendant resembles that worn by her daughter – the future Elizabeth I - in the Henry VIII Whitehall family group.

Scroll down for video

Alison Weir believes that a 19th-century engraving on an internet shopping site could be a 'lost' 16th-century portrait of Anne Boleyn, Queen of England (above)

Weir, a specialist in Tudor portraits, said: 'It's a very exciting find.'

There are only two authenticated 'portrait types' of Boleyn, one in the National Portrait Gallery (NPG), the other in Bradford Art Gallery.

Each has jeweled initials and inspired numerous versions.

A 1534 medal - the only lifetime depiction - has a similar head-dress and cross to the engraving's.

Although other versions of the eBay portrait exist, including in the NPG Heinz Archive, they have been wrongly labelled as Joan Fitzalan, Lady Bergavenny, who died in 1505 or 1508, Weir said: 'That is far too early for this portrait's costume. It cannot be her.'

Crucially, only the eBay example bears clear initials that 'make you sit up', she added.

She pointed to further evidence in the carnation or a gillyflower held by the sitter.

In 'a whole language of flowers in Tudor portraiture', carnations symbolised love and fertility, gillyflower meant queen of delights and 'carnation' may derive from 'coronation': 'Put all this together, and it does look as if this print was painted to mark her marriage and Coronation.'

She praised research done by Howard Jones, a former farmer from Bath interested in Tudor portraits.

The original painting (left) was sold in 1842 to a London art dealer. There are only two authenticated 'portrait types' of Boleyn, one in the National Portrait Gallery (right), the other in Bradford Art Gallery

He is selling the engraving's photograph on eBay for £70, having stumbled across the portrait in a print-shop near Oxford, he said: 'I was struck by the face… [and] the lettering.'

Weir, who was alerted to it by her daily eBay search for Henry VIII's wives, has sold 2.7 million history books and historical novels.

Her latest is a series of six novels on Henry VIII's wives.

The first, Katherine of Aragon: The True Queen, is published next month.

The annulment of Henry's marriage to Katherine and his decision to wed Boleyn led to the break with the Roman Catholic Church and the Reformation.

But Boleyn was beheaded in 1536, having failed to produce a male heir.

Although one contemporary described her as 'not the handsomest woman', Weir said: 'She had sex appeal, for Henry at least.'

Another leading Tudor historian, Tracy Borman, joint Chief Curator for the Historic Royal Palaces and author of the forthcoming The Private Lives of the Tudors, said: 'I'm very convinced by this.

'It is hugely exciting. This could well be a Coronation portrait.'

The childhood home of Anne Boleyn, Hever Castle (above). Another leading Tudor historian, Tracy Borman, joint Chief Curator for the Historic Royal Palaces, said: 'I'm very convinced by this'

She was particularly persuaded by the A-pendant's similarity to that worn by Boleyn's daughter and the richness of the sitter's dress.

The long, thin face and high cheek-bones tally with contemporary descriptions, she noted.

The original painting was sold in 1842 from Strawberry Hill, the Twickenham castle to a London art dealer.

He in turn sold it to Ralph Bernal, a British politician and collector who died in 1854.

Then the trail goes cold.

Weir said: 'Someone might come forward and say they've got it.