Clare Wadsworth

When my mother died, in 2012, she passed her 50% share of the family house to my sister (who also lived there), and to me, who lived elsewhere. My father died in 2023, and he has passed his share to myself and my sister. In my parent's will, they included a clause that my sister could live in the house for as long as she liked. My sister is now thinking of selling the house, is there any Capital Gains Tax liability on my share of the house? It was not my principal residence, but it was my sister's? I am sure that my sister would not be liable to any CGT, but I might be? Many Thanks