i worked for a rep of ireland company in holland. the inland revenue told me i had to pay uk tax unless i was out of the uk for more than 6 months of each tax year but as the company also had a uk office they were uk registered.
if theres no record of you or where you are they can bill you for an estimated average years earnings worth of tax.
tax has to be paid somewhere and its up to you to prove you have .
speak to the inland reveue. ive always found them to be quite helpful and reasonable. even after i got caught defrauding them