As this post has hung around for what seems ages now it has made me curious as to my insurance cover, I knew I was cover for DOC's just thought I would clarify the small print so I checked it yesterday

Certificate states
I may drive other cars with the owners permission as long as I am not employed in the motor trade

Exclusions
Used to secure the release of a motor car not owned by me which has been siezed by or on behalf of any Goverment or Public Authority

Policy Booklet states
We cover you using your car and
Using any other vehicle that your certificate of motor insurance allows you to use in the British Isles

Quick phone call to my insurer reply was
You may drive any other motor car with the owners permission even if the said motor car in NOT insured by the owner