McHugh, who lived in Milton Avenue, Clitheroe, extorted money from the supermarket giant for several months, unaware that with each step he took, the police drew nearer to capturing him.

What follows is background to the case and details of how McHugh's blackmail plot eventually collapsed.

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Blackmailer McHugh tried to extort a million pounds out of Tesco after running up on-line gambling debts.

The former tax inspector and charity worker first threatened to contaminate food products on the shelves and then bomb stores in a series of letters. McHugh (52) had once boasted to friends how easy it would be to blackmail the organisation.

In the spring of last year, McHugh, who lived with his Russian girlfriend and her son in Clitheroe, decided to put his plan into action.

In the weeks and months that were to follow, he played an extraordinary game of cat and mouse with both Tescos and the police, who were hunting him.

He even tried to throw detectives off the scent by placing a forensic "red herring" on one of his blackmail letters. He stuck a single strand of hair under a stamp on a blackmail letter. It wasn't his and it was designed to throw police off his trail because he knew they would subject him to tests for DNA.

At St Albans Crown Court today, McHugh appeared for sentence, having earlier admitted blackmail charges and sending bomb hoax letters through the post.

He met his Russian partner while working as a teacher of English in Russia. She came back to this country with him but, by the spring of last year, their relationship was in trouble and he had run up gambling debts betting on-line.

He then decided on a blackmail campaign against Tescos in a bid to solve his financial problems. First he applied for a Tuxedo Blue Diamond pre-paid debit card account.

Then he set about contacting Tesco stores, demanding sums of money be paid into the Tuxedo account so that he could draw them out using the card. If they didn't comply, he would contaminate dairy products.

But, as the weeks went by, his threats became more sinister, saying that bombs would go off in supermarkets. First McHugh targetted stores near Dundee in Scotland in May of last year, then he switched to Tesco's Head Office in Cheshunt, Herts in June.

As a result, Hertfordshire Police took on the job of finding the blackmailer. Today it was revealed that Tescos made available money for McHugh to draw out.

Hertfordshire Police said the money had been made available to "draw out the blackmailer into the open".

Working out which cashpoint machines he was using, the police were able to obtain CCTV images of the blackmailer. The first transaction in which he was caught on camera was when he went to an HSBC branch in Clitheroe.

On this occasion, McHugh was careful to keep his face covered. He wore an industrial mask and had the collars of his jacket turned up.However, days later when he went to a TSB branch in Bolton, he was not so careful and, for the first time, detectives could see his face.

With his Tuxedo card, McHugh could draw out £200 a day and police were building up a picture of the area where he was operating in. In July of last year McHugh targetted 76 Tesco stores across the country. In each of the letters he was threatening that unless money was paid into the account, bombs would go off.

In fact there was a postal strike as he sent the letters and only 14 got through. On Saturday July 14th last year, 14 stores across the UK were forced to close, with fears that a bomb had been placed on the premises.

In addition, McHugh sent letters to the police, British Transport Police and local papers. They all began "A bomb will go on between 2 p.m. and 7 p.m. today Saturday" and then the names of the store.

McHugh sent one letter to Tesco's head office in which he said: "How did you like Saturday? Just a taster of what is to come if you don't deposit £200 a day into my account. The overall figure has now jumped to £1m. because of the trouble you have put me to.

"You have all the details of my account, so just keep it topped up please. Please don't think that there is anything personal in all of this (I like Tesco and enjoy its shopping experience) but if you get emotionally involved, it won't help - treat this as a cost of your business operation."

"Please do not underestimate me - I am absolutely desperate and blood will flow if you do not co-operate."

McHugh went on "I WILL destroy your business and others will pick up your customers. Keep me sweet so that I may draw £200 a day (I have no objection to your trying to catch me out at the hole in the wall machines - why not? Life's a game anyway.)

"But do not ignore me or think me a fool because I'll crucify Tesco interests wherever I find them.

"A sensible approach will keep us all in clover - you know there is enough to go round for the brave. All best wishes for the continued success of Tesco."

McHugh signed himself off with the name "Arbuthnot the sign of the spider."

Police think this was a reference to a famous poem written by an 18th century poet about a spider. On a number of letters, he even sellotaped dead spiders to the paper.

He tried to throw police off the trial by sticking a piece of hair that wasn't one of his under the stamp. On one occasion a hand written letter had been penned in a child like scrawl.

McHugh even sent some of his blackmail letters bearing collectors stamps of the laughing policeman as if poking fun at the detectives he knew would be looking for him.

It was following a visit to Carlisle on July 23 last year that McHugh was arrested.

He had visited a cashpoint in the town and the transaction was immediately notified to the team of officers hunting him. They suspected he had strong links with Clitheroe and would even be returning back to Lancashire either by train or by car.

A team staked out Clitheroe railway station and he was seen getting off a train after it had pulled into the station.

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