In theory, yes she would. However it depends on the agreement between you.
She would have to demonstrate that she was living with you as your partner. How long had you been living together? Who paid the mortgage? Whose name was on the bills? Who paid the Council Tax? Did seh pay rent?
Is she was contributing to repayments on the mortagage, then why didn't she ask for her name to be added to the title deeds and ask for the mortgage agreement to be revised?
She would have to demonstrate that she contributed to the value of property above her housing costs. For example, you move in with a landlord and pay rent. If the landlord paid a mortgage would you expect to have a claim on the landlord's property?
A solicitor might argue that she was seeking to derive an undue benefit since the original investment (the deposit and mortgage) was yours.
Seek legal advice from a solicitor. Some Citizens Advice Bureaux offer a legal surgery where you can get half-an-hours legal advice for free.