If a councillor defects from one party to another, what data should they be entitled to take with them? Surely not canvass returns?

Cllr Ben Curran, a Sheffield councillor who defected from the Lib dems to Labour, has been reported to the police for doing so. It is claimed he downloaded the information onto a memory stick just days before defecting. A Lib Dem councillor, Cllr David Baker is complaining to the police.

The Star reports:

In a letter to chief constable Meredydd Hughes, Coun Baker says the party believes Coun Curran's actions may constitute data theft and a breach of the Data Protection Act.

The database will include people's voting intentions, which had been volunteered to Lib Dem canvassers along with mobile phone numbers, email addresses and details of Lib Dem councillors' casework.

Such information would be very useful to rival politicians.

The Lib Dems are demanding that Labour pledges not to use any of the information if it falls into their hands.

Earlier this week, Labour leadership favourite David Miliband welcomed Coun Curran, who was only elected in Walkley five months ago, to his party and said he wanted 10,000 Lib Dem members to follow his lead.

Voter information is alleged to have been downloaded from EARS, a data storage system used to hold information collected by canvassers. All parties gather such information, which is crucial for identifying potential swing voters and pinpointing issues of concern.

Coun David Baker said: "Local people have the right to know their personal information may now be used without their consent.

"Clearly this is very serious, that's why we're asking the Labour Party to fully co-operate with police."