I'm not keen on it at all, Margaret. When I've been to my local I've offered my name and phone number, but nothing else as I see it as a security risk. Others have taken it further and given false details for similar reasons.
Government departments haven't exactly got a good record of security and of looking after confidential details. The DSS once faxed me (a wrong number I assume) a claimants file. When I contacted them they weren't even bothered!
As regards your questions, a quick google reveals that there have been data breaches, but more worryingly, the data in some instances is being sold.
London Economic