CGT on an inherited property

What is the story with CGT on an inherited property? My partner should have inherited 25% of her father's house after he died intestate almost 30 years ago but was under the impression that the house should have passed to her brother as a joint tenant. Unfortunately it seems that they were tenants in common. My partner died 10 years ago and I was her sole beneficiary (not living in the UK). This has all come to light now. I don't want their house or the money but it sounds like CGT needs to be paid. I assume it should have been paid 30 years ago either because the house was sold or one sibling bought out the other's share? Or should it have been paid (for the same sort of reason) 10 years? Or would it only have to be paid some time in the future if the house were sold or one share was bought out? As I don't want the money could I sell it to them for a token amount and they pay HMRC whatever it deems the CGT should have been if it had been sold at market rate?

Hi Meekadoz,
CGT would apply at the time your partners share of the property was no longer hers, be that by selling the whole house of the brother buying her out.
Thank you.