Hi. I have bought a car in Jersey before and registered it in the UK. As long as the VAT and duty was paid on the car when registered originally in the UK and has not been subsequently claimed back upon export then the car can be imported and registered again in the UK with its original number. There is a small fee to pay from memory £45 I think and the car has to be MOT'd and insured. There is no import duty ect to pay when re-importing. Hope that helps.