Fraser forecast a rise in crime as burglars could easily spot which homes have analog alarm systems that no longer function. “Criminals will take advantage of any new weaknesses in home security they possibly can. They can use property websites and Google street view to scout out potential targets and assess the value of possessions in homes,” he said.

The Association of British Insurers warned non-working alarms could leave victims without any payout if they are burgled, as insurers could deny any claims.

BT said they are working together with alarm manufacturers and installers to inform customers of the dangers and the necessary upgrades that must be completed.

During the digital phone, rollout, some personal health alarms have also stopped working. Around half a million BT customers wear such devices to call for help in case of an emergency such as a fall or stroke. Customers are expected to cover the cost of any upgrades themselves, as BT has so far ruled out any financial assistance.