I’ve gone through all of the posts but can’t find out the answer to the following situation (and avoiding the question of tapered relief);
Year 1 - buy UK property <£200k and live in it as primary residence as UK tax resident
Year 10 - buy a holiday home in France
Year 15 - UK house is valued at >£400k. Move to holiday home in France, become French taxpayer, holiday home becomes primary residence. UK property becomes secondary property.
If in the future the UK secondary home is sold, what value would the French Authorities use as the base point for the calculation of CGT?