A nice trade in tiaras: Glasgow Airport sells off Duchess of Argyll's very posh lost property

A diamond tiara is not among the usual items handed in to the lost and found department at Glasgow Airport. But when £100,000 of jewellery, including a Victorian headpiece, was found by the British Airports Authority (BAA), they sold it on rather than tracking down its distraught owner who had reported it missing several months before.

The Duchess of Argyll lost four items of jewellery in a bag in Glasgow Airport in 2006 as she returned from London to Inveraray Castle, Clan Campbell's ancestral home.

She reported the incident to police and the Art Loss Register (ALR), which listed it on its database of stolen antiques but the trail went cold. That is until earlier this year when the Duchess happened to spot one of the pieces – a Cartier brooch – in a catalogue of Scottish auction Lyon & Turnbull (L&T).

The ALR's lawyer, Christopher Marinello, investigated and discovered the jewellery had actually resurfaced just months after its loss, but BAA did not inform the police. It simply sold it off to a diamond merchant for less than £5,000 – a fraction of its value – and gave the proceeds to charity, its usual procedure for lost property unclaimed within three months.

Mr Marinello said: "Apparently, the airport found the jewels or they were turned in to 'lost and found' by someone... The question remains: what did they do to help find the owner? They didn't call the police even though the airport police had a record of the theft. They didn't call ALR. The only thing they did was sell them." He established the brooch was consigned to L&T by someone who bought it in good faith from the diamond merchant.

The Duchess, 68, voiced "disbelief" at BAA's action over the case. The authority has since offered to reimburse the diamond merchant in order for the tiara and brooch to be returned to her although an emerald ring and pearl earrings are still missing.

She added: "I'm absolutely amazed. I thought that after six years I'd lost them forever. The tiara was a Victorian family one and the necklace was given to me for my 21st birthday. So everything was very special. "

The Airport Authority says they no longer have records relating to the incident but a spokesman said they would rethink their procedures as a result of the case. "We have since assisted the police with their recent enquiries and paid a sum equivalent to the money raised from the sale to enable the items to be returned to their rightful owner," he said.

Gavin Strang, L&T director, said he was "delighted" that the jewellery was being returned to its "rightful owner".