Equity share EX won't accept buy out

Looking for advice.

Friend owns a house, her ex moved out approx 12 years ago after living together for about 2 years.
Since then he has not paid into the property at all

She now wants to take his name off of the property which he has previously agreed but has since u-turned despite claiming he never wanted anything out of the property multiple times over the years and even said he would sign anything just get the papers drawn up.

He now thinks he is entitled to 50% of todays equity.

My question is, is he entitled to the equity based on todays valuation or would the fact he has not contributed in any way other than the time he lived there mean he would only be entitled to a smaller amount?

They have offered him a token amount but he now says he wants another £10k on top of that, they don't have that kind of money and have pointed out he would most likely spend more than that taking them to court.

I would appreciate if anyone who has experienced this could offering advice or inform of the likely outcome.

Thank You in advance

When you say that since he left he has not paid into the property at all this overlooks the fact that during that time his ex has had the benefit of living in the property and he has not. In fact she has had the benefit of living in a property half owned by him so he has an arguable case for saying she owes him rent for his half. The fact is that he is a joint owner of the property and on the face of it a joint owner's basic entitlement is to half the value of the property and that means its value now not what its value was when he left.

Having said all of that, it is actually impossible to tell what he would actually get from a court in these circumstances. That is because you do not say whether they were married, whether they have obtained a divorce, whether there are any dependent children, what the respective incomes of his ex and him are, where he now lives, whether he has bought another place to live, what the property is worth now, what the outstanding mortgage etc.

There are a whole range of factors that could affect the possible outcome. There is not information in this post to be able to hazard a guess.