Paid by landlord to end tenancy early

I was paid by an overseas landlord to end my tenancy on an overseas property that I was renting (renting myself, not letting out nor subletting). Because they wanted to sell it to a developer. I got paid about £15,000 equivalent to relinquish my tenancy rights. I do not know how/if this should be declared for tax - is it CGT? If so, what would be acquisition cost as it would have cost the same to ask me to leave at the start of the tenancy!

Hi,
You can see guidance here:
CG72300 - Compensation: displaced tenants: general
Thank you.