Thanks for the reply. But I kind of see it as have a huge cake but not get to eat any of it!!
He would still be working for the same company - albeit a different branch - so we didn't expect him to lose his years of service accumulated thus far. It could be that the pension arrangements are totally different across their offices so maybe that was naive on my part (pensions, or any sort of benefit like that are an alien concept where I work!).
On the other hand: to work in a country that doesn't deduct any income tax, and pay full taxes to a country you're not resident in - doesn't seem like a good deal at all!
We will have to weigh the options up, I just wondered as a non-resident, could you claim back taxes you paid.
We will definitely seek professional financial advice on this one. Thanks again.