Car dealer test drive car insurance

[drew.h]

If I'm going to test drive a car from a small back street dealer, what proof should I ask for that the car is insured? Should I just go off what AskMID says?

I was thinking about asking for a test drive tomorrow, so checked the car on AskMID, which says its not insured. I check a few more cars from same dealer and none are insured. I checked other cars at different dealers and they all show as insured.

I should avoid that dealer?

[drew.h]

Does the dealer need to be in the car for the insurance?
Does the dealer need to attach trade plates, or are they for when there is no road tax?
Does the car need to have a valid MOT?

I don't normally buy from dealers and my last experience was/still is unpleasant.