I was in the UK last week and met officials at the Treasury, just a follow up discussion.
However one official is now responsible for dealing with cross-national tax issues, specifically ensuriing that in his case, ensuring that the details of any income earned in the UK for Brits living in the EU will be collated and passed onto HMRC and then onwards in our case to the Impots in France.
A new system/procedure has been created for this purpose which will replace the existing procedure in September.
So, if any of you are tempted to avoid tax in France on UK income, may I suggest you think very carefully.