Capital Gains Tax on sale of property overseas - Double Tax Agreement in place

I understand there is a double tax agreement ( DTA) in place between UK and Mauritius. My wife and I we bought a house in Mauritius in 1993, the house was sold in February 2024. The house was our main residence until September 2009 before the family moved to the UK. On sale of the house in February 2024, Land Transfer Tax (5% of sale value) was paid to authorities in Mauritius. Questions: 1. Is CGT payable, though Land Transfer Tax was paid to Mauritian authorities in February 24? 2. Does the DTA apply to reduce or nullify CGT? 3. If CGT is payable, how is it calculated, taking account of currrency differences in 1993 and 2024 and the fact that the property was our main residence till 2009? 4. If CGT is payable, how is it divided between me and my wife? Thanks very much

Hi,
Article 13 of the tax treaty between Mauritius and the UK allows both countries to charge capital gains tax on the disposal of your property in Mauritius.  
Mauritius: tax treaties
The treaty allows for you to claim a credit of up to 100% of the overseas tax paid. You will need to work out the UK capital gains tax liability, using UK Capital Gains Tax rules. All values in your calculation must be in pounds sterling, using a just and reasonable exchange rate in place at the time of acquistion and disposal.  Under the terms of Self Assessment, we do not provide an official exchange rate and the onus is on the individual to use a just and reasonable exchange rate for each acquisition and disposal.  
For your convenience, there are exchange rates at:
The National Archives: Exchange rates from HMRC in CSV and XML format
For older rates at:
Foreign exchange rates and spot rates: 1 January 1989 to 31 March 2009
You are free to use any of the supplied rates or one of your own choosing.
To help you work out your UK capital gains laibility, there is a calculator at:
Tax when you sell property
As the property was your main residence for a period of time, private residence relief can be applied to reduce any gain.  
Please have a look at helpsheet HS283.
HS283 Private Residence Relief (2024)
As you are married, you split the disposal on a 50/50 basis.
Thank you.