... In the meantime, i'd get the driver to ask for a recording from the insurance company from when they phoned and confirmed drive other car was in place. The key word is 'permitting' you did not permit it, teh driver not only told you they was insured they took additional steps to check they was insured. That is not a defence for them, but it is a defence point for you...
Isn't it a problem that the US insurance company never cofirmed that the OP's sister was covered because - for some God unknown reason - she never thought to mention she was visiting the UK and that that was where the cover was needed? Any recording from the insurance company is likely to confirm that she wasn't covered rather than that she was.
I'm all for the OP pleading not guilty - if charged with permitting to drive without insurance - on the basis that his sister assured him that she was covered and he had no reason to disbelieve her. But I don't think a recording from the US insurer is likely to help that plea.
I'd also be concerend that a court might consider that most UK drivers would know that a US policy would not cover someone driving in the UK.
(If I were the OP I'd want my sister to pay any fines and increased costs stemming from this...)
