A laptop containing the personal details and signatures of more than 14,000 St Albans people have been stolen from the district council, the Review can reveal.

District council officials realised last week that a laptop containing the names, addresses and dates of birth of 14,673 people – everyone who applied for a postal vote for June's local election – was missing.

They believe it was taken by the same opportunistic thief responsible for the disappearance from the council offices of three other laptops earlier this month.

The signatures are viewable as the laptop includes scanned postal vote application forms.

Council spokeswoman Claire Wainwright said: “ Name and address information is, of course, publicly available via the Electoral Register, except where people have opted out. No details of the votes cast were on the laptop. The data was protected by two levels of security access.

“There is a slight risk that the data could be accessed and as a precaution, the council is writing to those residents who have been affected to inform them of the position and the risks involved.

“The council is working with the police and Northgate Information Solutions, which manages its IT services, to investigate the matter.

“The Electoral Commission and the Information Commissioner’s office have both been informed.”

Chief executive Daniel Goodwin said: “I would like to apologise to residents and reassure them that the council takes its responsibility to look after their personal data very seriously.

“I have asked the head of internal audit, Piyush Fatania, to conduct an internal investigation with immediate effect. This will reveal whether there is a need for further security measures to be put in place and if so, we will of course take immediate steps to implement these.”