Explained in terms as simple as possible Folkiedave if you are taxed at source you can still use ways of reducing the amount of tax you have to pay, all you have to do is claim it back. Now what is it about that, that you a former university lecturer, cannot grasp.

Yes paid tax in the UK for years, Folkiedave, in all probability a damn sight more than you. I also used the services of an accountant to make sure that I paid only what I had to. Many working in the same industry as myself, while not going to Monaco did go to live in France or elswhere abroad. In the former if you worked outside metropolitan France for more than six months of the year you did not pay state taxes, you only had to pay the local tax for the area you lived in.

As for spouting bollocks:
The definition:
"Tax avoidance is the legal utilization of the tax regime to one's own advantage, in order to reduce the amount of tax that is payable by means that are within the law. By contrast tax evasion is the general term for efforts by individuals, firms, trusts, and other entities to evade taxes by illegal means."

So what I said originally - "I can never remember which is illegal and which isn't tax avoidance I believe is legal, whereas tax evasion is not." - would appear to have been right on the button and not bollocks at all Folkiedave.