Tesco and its ever-popular Clubcard was once caught up in a terrifying blackmail plot that saw a disturbed customer threaten to put his HIV-infected blood into food.
Back in 1995, a shopper called Frank Riolfo claimed he had the disease and warned he would contaminate the products unless the supermarket created a card to pay him an eye-watering sum of money.
Riolfo told bosses to pay him £250,000 via the plastic card after calling the Tesco store in Kettering, Northamptonshire, calling himself St Mary-Ann.
Telling bosses Riolfo he had infected the food at the store, panic set in.
Staff eventually found a pack of frozen peas and prawns injected with black ink but the panic wasn't over.
Days later, he sent a blackmail demand to head office saying they should creature the card as a safe way to pay him - or he would do it for real.
'"As you know by now, the food was contaminated with pen ink. It could so easily have been a toxic substance," the letter read.
"I am fully prepared to extend my actions unless my demands are met.''
Chillingly, the former lance corporal in the Royal Army Medical Corps added: ''I have AIDS. So I have a ready-made supply of infected blood.''
Tesco initially refused to enter into conversation with the man.
But, concerned by the possible repercussion, they suddenly had a change of heart and launched the Clubcard promotion at the Dudley store, and agreed to hand over thousands.
The cards carried secret details so Riolfo could withdraw the cash.
He demanded Tesco place the PIN number in a coded advert in The Times.
Once he had all the information, Riolfo and his wife withdrew the cash from ATM's around England.
But in April 1995, the game was up and the pair were arrested at a cashpoint in Slough, Berkshire, having managed to steal £7,000 before being caught.
He was jailed for eight years by Northampton Crown Court after admitting everything.
Tesco say the decision was made to launch Clubcard in November 1994, two months before this blackmail case.
The cards are used today by more than 20 million people in the UK.
A Tesco spokesperson said: “Tesco launched Tesco Clubcard to give our customers great value and rewards after over two years of dedicated insight and research - and today it is used by over 20 million households.
"The decision to launch is completely unrelated to this issue.”
