Limitation Act 1981

An action to redeem mortgaged property in the possession of a mortgagee is not maintainable against that mortgagee if brought after the expiration of a limitation period of 12 years from the date on which that mortgagee or a person through whom he claims last:

went into possession of the property; or

received a payment of principal money or interest secured by the mortgage from the plaintiff or from a person through whom he claims,

or, when both things happen, the later of those dates.