On Monday, seven cars were stolen in just one hour from driveways in the upmarket Shirley area of Birmingham and nearby Wythall, Worcestershire.

In total, more than 20 vehicles, including Mercedes and BMWs, have been driven away after owners returned indoors while windsreens de-iced.

Inspector Steve Glover, from West Midlands Police, said the gang appeared to be targeting well-off areas and all the thefts had occurred on frosty mornings.

He pointed out that owners' insurance policies could be void if cars and their ignition keys were taken.

Inspector Glover advised motorists to stay with their vehicles or use a scraper to remove frost and ice.