If he hadn’t taken the mortgage on that the house wouldn’t form part of the estate would it? And you wouldn’t be fighting over it. It’s clear from the timing that he surrendered his interest in the house on the basis of your mother’s promise to leave it to him when she died. I believe you are fighting a losing battle, and this small estate will only get smaller the longer you do so. As I have already said, what would you and your sisters do if the judge awarded him the house and ordered that you all pay his costs? That is highly probable. He has made an offer of £50k plus payment of his legal costs, which you have been driving up by refusing to accept what seems pretty obvious to me. He isn’t claiming the whole house despite my belief that he could. Whether you think so or not, his offer is generous. You are letting his having paid the mortgage for only a short time cloud your judgement. I have explained what promissory estoppel, which he is claiming, is - and here we have a very clear example of it.