I have a friend who has been living with her partner for 10 years and they have two children together but not married. Her partner had just purchased a property so the mortgage was in his name and they initially expected to change this before their marriage and children came along. However they did not get around to doing this and now the relationship has broken down. She has been advised that because her name is not on the mortgage or the deeds that she has no legal right to have any share of the property even if she can evidence that she is on the council tax and has been a resident for the past 10 years. She also has documentation for the life assurance and critical illness which states that they are to be married but not on the mortgage protection. Does she have any right whatsoever to a share of this property legally

Please clarify what country this situation is in (I'm guessing UK?), and if in the US then what state?

In general her right to any part of the property would be determined by whether her name is on the deed - if not, then she is not an owner. The mortgage really has nothing to do with it. And from the description it seems that the man brought the property into the relationship (I assume that's what you mean by "Her partner had just purchased a property"), therefore in general it is his to keep after the relationship breaks up. If this is in the US then depending on what state it's in there may be an opportunity for her to claim common-law marriage and from that stake a claim to some of his assets. So again - where is this?