A coin collection rated as one of Britain's most historically important, including pieces dating back to as far as the 10th century, has been stolen.

Specimens including up to 1,000 of Scotland's oldest minted coins worth more than £500,000 were taken from the home of Lord and Lady Stewartby in the Borders region of Scotland on Wednesday night.

The theft was described by historians as a "total disaster" for the country's heritage.

The stolen coins are thought to include one struck under the reign of Robert the Bruce 900 years ago, and further items dating to the period of David II in the 14th century, and James I and James II in the 1400s.

Lord Stewartby, one of the country’s foremost coin experts and a former minister who introduced the £2 coin to the UK, had spent more than 50 years amassing his collection.

It is understood he was in the process of creating a full catalogue of the items when they were stolen. He has offered a “substantial” reward - believed to be a six-figure sum - for information leading to their recovery.

Lord Stewartby's daughter Lydia Pretzlik, 71, said her father, a former MP, was devastated at the robbery, which had deprived him of a substantial amount of a collection he had amassed over a 50 year period.

“My father spent his whole life building up the collection,” Mrs Pretzlik, 38, said. “He had just retired and was looking forward to creating a catalogue.

“The coins were available to be used by other people for research, that was always the plan.

“I think he was shocked and disheartened by the theft. He just wants the coins back so he can catalogue them.”

Nick Holmes, senior curator of numismatics at National Museums Scotland, described the loss of the coin collection as a “total disaster” for the country.

“Lord Stewartby had been putting this collection together over decades," he said. “One of his main reasons for doing so was so it could be used as an academic resource. The collection is unique and important both for its quality and quantity.

“This theft really sets back studies in Scottish coinage - it is a total disaster.”

A spokesman for Lothian and Borders Police said: “This collection is a unique part of Scottish history and its loss cannot be underestimated.

“We have carried out a significant amount of inquiry so far and are now appealing to the public for help.

“We would appeal to anyone who may have information as to the whereabouts of the collection or anyone who has been offered some rare and unique coins”.

Before being ennobled as Lord Stewartby in 1992, Ian Halley Stewart was Conservative MP for North Hertfordshire from 1974 to 1991.

He served as junior minister for Defence Procurement and Economic Secretary to the Treasury and, in 1986, he was responsible for introducing the £2 coin to Britain.

Times Recommends

• Anne Darwin's performance of a lifetime
• Renaissance for canals as new boaters come aboard
• Case study: forced to marry a cousin at 17