Since July this year, thefts have shot up from 2 to 48 across the county; 24 of them were in the month of October.

Watford has been highlighted as a particular hot spot, with six thefts in four months.

Most offences have been on Thursday or Friday afternoons, in the vicinity of motorways, which allow the criminals to make a quick getaway.

The typical method of entry is by breaking windows.

They therefore advise that drivers remove all traces of these systems when the vehicle is left unattended.