Compelling new evidence suggests a tartan shawl owned by Tennyson – one of Lincolnshire's favourite sons – was a unique present from Queen Victoria.
Grace Timmins, from Lincoln's Tennyson Research Centre, has identified the fabric as Balmoral Tartan.
Nowadays, Balmoral Tartan can only be worn by Queen Elizabeth II, a select few royals and her personal piper with her express permission.
Lincolnshire bard Alfred, Lord Tennyson, was Poet Laureate for much of Victoria's reign, and it is thought she may well have bestowed the honour on him.
Collections access officer Mrs Timmins made the link as she prepared to exhibit clothes and accessories from Tennyson and his family.
"I thought it was about time to research properly the lovely tartan shawl that was in tissue and in a box, but without any information," she said.
"My heart sank a bit when I realised there were over 4,000 registered tartans, but I thought I'd pursue the tradition that it was a gift from Queen Victoria.
"It didn't take long to realise that what we had was a treasure: the Balmoral Tartan designed by Prince Albert particularly for Queen Victoria in 1853.
"It's the one and only tartan which cannot be worn by anyone unless permission has been expressly granted.
"It's predominantly grey with overchecks of red and black. The background contains a thread of black and white yarns twisted together to achieve the appearance of the rough-hewn granite, which, I must say you have to work quite hard to see.
"It is worn by Queen Elizabeth II herself as a skirt and several members of the Royal Family, but only with her permission,'' added Mrs Timmins. "The only other approved wearer of the Balmoral Tartan is the Queen's personal piper – so I wonder whether that's why Tennyson was given it – as Queen Victoria's poet laureate he was, in a way, her personal piper."
Brian Wilton, director of the Scottish Tartans Authority, said: "Balmoral Tartan is not something you can pop out to the local tartan shop to buy.
"It makes sense that as an item of clothing made from Balmoral Tartan, a gifting would have had to have been authorised by the Royal Household."