A woman walks past the Swiss Cottage branch of Barclays bank in London Reuters

Former acid house rave organiser turned cyber criminal Tony Colston-Hayter and his gang blew a fortune at Harrods and Selfridges after stealing £1.25m through trojan horse attacks on computers at branches of Barclays Bank.

The gang used a hardware device called a KVM switch, which allows workers to access their computer systems remotely, to steal more than 24,000 credit cards from American Express and Coutts customers.

One of the KVM switch devices, which can be bought for as little as £10 over the internet, was found attached to a 3G router of a computer in the Barclays branch in Swiss cottage, north London.

Police said this method of tapping into personal data was a "rapidly evolving" field of cybercrime.

"This new methodology demonstrates the rapidly evolving nature of low-risk, high-financial yield cyber-enabled crime," the Metropolitan Police said.

In September last year, police seized thousands of credit cards and personal data, as well as, cash, jewellery, and drugs in a raid across properties in Westminster, Newham, Camden, Brent, and Essex.

Barclays has since recovered £543,000.

Colston-Hayter has known as the "Acid House King". He famously handcuffed himself to Jonathan Ross after his Sunrise parties were banned by the then Home Secretary Douglas Hurd.