Some 70 per cent of dementia sufferers are at risk of going missing at least once, according to data gathered by the University of East Anglia.

Avon and Somerset Police has secured 30 of the devices, which will be offered to the most vulnerable, based on risk assessments.

Mindme said it would be offering the GPS trackers to other forces.

Simon Wolf, who is head of the company, said: “Unfortunately there are people who go for walks and can get lost or confused. Then it involves a major hunt for them. This is a more flexible system.”