Proprietary estoppel arises where one person makes a representation e.g. promise or provides an assurance to another person and that person’s acts in reliance upon it to their detriment.
That you had a genuine belief at all material times that the deceased intended to make a gift to you.
That the deceased had actively encouraged that belief.
That you acted in reliance on the assurances that the deceased had made to you to your own detriment.
Turning your own life upside down by leaving your home (and possibly giving up your job) in order to move in and care for someone in reliance upon representations that they had made to you i.e. if you did this that they would leave their home or estate to you.
It is often used in order to establish a right to claim an ownership of property or a share in property. This can be where despite having made representations that the property will be left to a person that they then leave it to someone else in their will. Or where there is no will and the property then passes to someone else via the intestacy rules.
The time limit that applies is determined by the situation, best advice is to seek legal advice at the earliest opportunity.
The court has complete discretion and can grant the relief that it considers fair in all the circumstances, this can include granting a right to live in the property for life, a share in the property, or that the property be transferred into your ownership entirely.