Date of Purchase in calculating Capital Gain in foreign shares

I have shares in my French bank account and I want to sell them. The French bank refuse to provide me with date of purchase because they provide the capital gain/loss. I need the date of purchase to calculate any gain/loss due to currency. Is there a way to resolve this?

Hi,
We cannot advise how to obtain the figures from your bank.  
If you are resident in the UK, then the gain will be taxable in the UK and not France.  
You should request a certificate of residence How to apply for a certificate of residence to claim tax relief abroad.  
This can be given to the French tax authorities, to show the gains are taxable in the UK.
Thank you.