Well that has hardly been effective over the years has it - considering that at one time (maybe even still, if he's not dead) maybe half of BT was owned by a very shadowy figure whom (as a matter of record) UK HMRC were vigorously pursing for decades, to absolutely no result.
For the avoidance of doubt, the person to whom I refer is not Scottish and probably 90% of you will never have heard of him.
In fact Mr Jellybean - can you name anybody who has been apprehended under these laws and treaties?