SHOPPING online can save you hundreds of pounds a year on high street prices. And now, as well as comparison and cashback websites, dedicated e-shoppers have a new money-saver to factor in — the “promotional code”.

The codes are the 21st-century answer to the discount coupons mailed out to catalogue customers for decades. These short strings of letters and numerals, for example FUN1, are e-mailed to loyal customers or printed in magazines and newspapers as reader promotions. Most entitle the user — who types it into the “promotional code” box at a store’s checkout — to a discount or free delivery.

The majority of codes — which are time-limited — are sent with terms and conditions restricting use to one sale per person or household. Some encourage the recipient to pass the code on to friends. Others restrict use to a named recipient or first-time customer.

The codes have been seized on by savvy shoppers, who e-mail them on, and post them on blogs and message boards, often without terms and conditions. The latest development is the emergence in recent months of free websites promising up-to-date codes for scores of big-brand e-retailers, including Amazon, Comet and Boden.

One of these sites is www.myvouchercodes.co.uk, the brainchild of Mark Pearson, 26, a web designer. Mr Pearson says that discounts of 10 or 20 per cent are typical. The codes at his site are sent in by web users and checked before they are posted. Among the discounts listed are 20 per cent off at John Lewis and 10 per cent off at The Body Shop and HMV. “It gets addictive,” he says.

Fine in theory, but my experience of the site was mixed. Most codes are entered before credit or debit card details, so can be tested safely. None of the codes I tried for John Lewis or HMV was valid — presumably they had expired — but I did notch up potential savings of 20 per cent at Thornton’s and Early Learning Centre and 10 per cent off at The Body Shop and Bag of Sweets.

That kind of discount is bound to draw interest. But is use of the codes which are not consistently listed with their terms and conditions legitimate? What are the chances of making a fraudulent transaction?

Minimal, according to Richard Webb, of the Government’s Trading Standards Institute. He says that it is up to retailers to vet customers and to control code use, as it is inevitable that they will be widely circulated: “Tapping in a code does not constitute a deception.” James Roper, of the Interactive Media in Retail Group, the industry body for e-retailing, agrees: “You can’t blame consumers for having a go.”