A spate of vehicle thefts across the borough has sparked a police appeal to residents.
Drivers are being urged to keep their vehicles locked at all times, and to store keys in a safe and secure place.
Thieves have been stealing keys that have been left inside homes, close to letter boxes or insecure windows and doors, enabling them to drive the vehicles away.
Dacorum has seen a 23 per cent increase in vehicle thefts compared to this time last year.
150 thefts were recorded since April, up from 122 offences in 2017.
Police are now issuing advice to residents to keep their vehicles secure.
Inspector Andrew Palfreyman from Hertfordshire Constabulary said: “Most of the newer vehicles in the UK now use very sophisticated security systems, however criminals are using technology which enables them to bypass these systems allowing them to gain access and steal vehicles.
“You should never give anyone you do not know access to your keys or vehicle and when using remote central locking check the door to ensure they really are locked before leaving your vehicle.”