Got it slightly wrong (my tax exams clearly didn't make it all stick)

Basic thing is if you earn money overseas and you are not resident in UK (resident is determined by virtue of how long you are in the country in a tax year) then you don't have to pay anything even if you repatriate the money.

See

http://www.direct.gov.uk/MoneyTaxAndBenefits/Taxes/LeavingOrComingIntoTh...