Having to sign for a newspaper or a chocolate bar in a newsagent was the norm before Chip and PIN, and now even that has become a chore since contactless payment was introduced.

But as much as many of us undoubtedly treasure the convenience of using contactless, and how it has revolutionised our money-spending methods, should we be concerned about reports that it has enabled a new wave of modern-day pickpockets?

One in 10 card payments are now contactless, The UK Card Association said in October, and although we hear more and more about contactless cards - word on the dangers of having one seems to slip through the net.

Roi Perez, community manager of the Twickenham based SC magazine - a computer security magazine - claims £20 was stolen from his card through an unauthorised contactless payment on his journey home from work.

A man bumped into him on a crowded South West train, he said, and continued to stand "suspiciously" close to his wallet.

He said: "It didn't feel like a casual bump on a busy train, where people bump into you constantly, he stayed there for a little too long and I felt very suspicious about it."

Mr Perez then realised an "illegal transaction" took place, called his bank, and the stolen money was refunded.

Is this the modern day Fagin, equipped with a card reader, using the underground to operate as commuters scuttle around tapping in and out?

There are no statistics available to suggest just how common these contactless thefts are, and the London Transport Police say they have no record of any theft or fraud related to contactless payments.

However an investigation by the consumer magazine Which? found last year saw researchers use readily available card readers to "steal" crucial data from contactless cards, which could then be used to spend online.

The researchers used 10 different credit and debit cards - all meant to be coded to "mask" personal data - and were able to read the data that was supposed to be hidden.

Richard Koch, head of policy at the UK Cards Association, said: "Instance of fraud on contactless cards are extremely rare, with less of less than a penny for every £100 spend on contactless."

He added that additional data such as the cardholder's address and card security code are needed before a purchase can be confirmed.

But with the "stolen" information, Which? were able to order a £3,000 TV from a mainstream online shop under a false name and address.

Although Which? exposed these flaws, a spokesperson said that consumers should still feel confident using contactless, but there is good reason to be concerned.

Card readers used for the investigation are readily available to buy online and, according to experts, can be tampered with to take money from cards at a distance. So now we're not just dealing with a modern-day Fagin, but a full-on virtual money-sucking monster.

Mr Perez said: "The card readers are so readily available now, once you get hold of one you can modify it and do whatever you want with it."

Peter Eisenegger, privacy standard expert at the National Consumers Federation, was part of an expert group that developed European Standards covering the use of contactless cards.

"It may be possible for a small percentage of cards to be read 15 to 20cm from the reader," he said.

"It is vital to protect consumers from fraudsters who have the know-how to develop mobile card readers with much greater reading distances than those used by retailers."

He said that considering the volume of contactless transactions taking place, even if this was to occur to 0.1% of cases, many consumers could be affected.

Mr Perez is sure there is no a way to intervene with this revolutionary method of payment.

He said: "I definitely think that contactless cards are a good thing overall, because for a consumer they make a huge amount of sense.

"But there is a huge argument to say that they are susceptible to theft, and while it is something we cannot avoid, people need to be super, super vigilant.

Credit card covers known as 'card shields' are now available to prevent data being stolen from contactless cards. This is a more sophisticated method of protection, next to lining your wallet with foil.

Does this mean people are living hopelessly with contactless paranoia? If it does then the growing trade in card shields suggests they may not be alone.