Anyone know of any insurance companies which will insure a 21 year old and the cover includes being able to drive any other car with the owners permission?

Norwich Union want me to pay £1100 next year for a 21 year old with 2 years no claims, on a Laguna dti! Third party only!!!

Most other insurance companies won't let me drive any other car on the policy, and I feel this will be needed for the mk1! (Wouldn't like to quote that in my name!)