Sheep farmer Nigel Wright laced jars of baby food in Lockerbie’s Tesco store with metal shards in an attempt at blackmailing the chain.

His campaign to extort £1.4 million in cryptocurrency from the chain lasted almost two years and led to Operation Hancock - the largest blackmail investigation ever conducted in the UK.

At various points there were more than 100 officers deployed across the country on the case, and at one stage there were in excess of 30 officers watching CCTV footage on day and night shifts.

Wright was eventually arrested on February 25 following an investigation led by the Bedfordshire, Cambridgeshire and Hertfordshire Major Crime Unit with the help of the National Crime Agency.

Also involved were the Food Standards Agency, Food Standards Scotland, Public Health England, Public Health Scotland and Police Scotland.

Assistant Chief Constable Bill Jephson, who led the investigation on behalf of Hertfordshire Constabulary, described it as the “most serious and most challenging” product contamination case ever dealt with in the UK.

Mr Jephson said there was “very significant” concern over whether there were more contaminated jars of baby food, adding that he is confident everything that needed to be removed from the shelves was removed.

Deputy Senior Investigating Officer Lucy Thomson said: “He’s clearly a man with some significant knowledge and understanding of how the internet works, and unfortunately put the understanding and knowledge to such negative purposes, which is a great shame.

“But in terms of his motivation, he’s the only person who will ever truly know why he did what he did and put so many people at risk, including his family, and their livelihood.”

She said his knowledge and understanding of how to manipulate cryptocurrency was “effective”.

Ms Thomson said Wright’s defence - that he was being threatened by travellers - changed throughout and he maintained no consistency with that defence.

“We haven’t uncovered any evidence that supports that defence,” she said, adding that inquiries were “extensive”.

Ms Thomson said cases like this are “incredibly scarce”, adding: “I’ve never investigated a crime like this or been involved in an investigation of this breadth and severity.”

She described what Wright did as “absolutely disgraceful”, adding: “I think his crime was absolutely horrific and of the most cynical nature, putting babies at risk, and mothers, feeding their children.

“I don’t think it gets much worse.”

Mr Jephson said: “He should be absolutely ashamed of what he has done and I hope he gets the justice that he deserves.”