I have had motor traders policy/business policy on my insurance for a while and this has meant I am insured to drive any car for trade purposes. I own a repairs garage and was driving a friends car to my garage quite late at night so I would be able to work on it the next morning and was stopped by the police. I told them I had the traders/business insurance cover and they said it did not apply at this time of day. I wasn't aware there were time restrictions to the use of my policy. Has anyone ever heard of this before?

I have to say i never heard of this. I am an Insurance agent in NY and that isn't an exclusion on any of our policies. I also know that her insurance should cover it too, if she has any on the car. I know in NY as long as the plates are insured then it is ok on any car, being dealer plates. if it is a personal car with personal plates then it is insured on her policy.