How to insure cars in the UK with US registration?

Hello, fellow adventurers,

My husband and I are importing our car from the US to the UK. As my husband is a student and we’re in the UK for a set period, we qualify for customs relief and intend to keep the car registered in the US. However, we’re having extreme difficulty finding insurance. UK companies won’t insure a car with foreign registration, and we haven't found a US company who will insure a car abroad. A friend got a Geico International plan several years ago, but as of April of this year Geico stopped insuring international students and tourists. Has anyone gone through this before? Google searches and many phone calls with insurance companies on both sides of the pond have yielded nothing. Thank you for any help you can provide!