Insuring a second car

Currently I use my Elan as my everyday car to and from work so on average about 12 miles a day and what with the amounts of events I tend to go along to I have become worried over milage issues on my Lotus and so will be looking at getting a run around car to take the pressure of the Elan. I will still use it most months for meets etc and for those lovely British weekends.

I have my car insured with Lancaster Classic Car Insurance but am slightly in the blue as to whether insuring just myself on another car is likely to cost me just a little extra or a whole lot? I'm sure there are plenty of you out there with several cars so please share your wisdom ...