Tesco is planning a national rollout of scan- as-you-shop devices after trials revealed one pound in every seven spent in its stores goes through the system.

The retailer is piloting the scheme in 60 stores but plans to roll them out to a further 40 before Christmas and is looking at UK-wide adoption.

At a tour of one trial store, in Bishop’s Stortford, Herts, CEO Philip Clarke said he regretted Tesco had been so slow to roll out the self-scanning devices. “This had actually been in trial for two years in five stores but became stuck in development,” he said.

The devices, which use a portable barcode scanner that can be checked out at a self-service system at the front of the store, had also proved an unlikely hit with children, said Clarke, claiming many were helping their parents scan as they shopped.

Tesco’s initial reluctance to roll out the devices is understood to be down to fears they would increase customer thefts. But the retailer has been working with electronic tagging company Checkpoint Systems to roll out new security tags compatible with the devices.

The scanners were already proving popular, said Tesco chief operating officer Chris Bush. “The devices have been in this store for eight weeks and it’s already accounting for 15% of transactions.”

Mobile scanners are not new to grocery. They were trialled in the 1990s by Safeway, and Waitrose has been offering a service called Quick Check since 1996. The retailer offers the service in 178 stores and said it too had plans for more as they accounted for up to 25% of sales in some stores.

“Customer feedback is extremely positive, with the main benefits quoted as being convenience, time saved, ability to track spend and not having to queue at the checkouts,” said a spokeswoman.