Before proceeding further, it is necessary to clarify the meaning of the phrase “subrogation to extinguished securities” – an expression deployed by Da Hui in its prayers for relief. Academic commentators have used this expression to account for the fact that the security in the hands of a creditor will almost invariably be extinguished (usually by operation of law) upon discharge of the secured debt. However, the court may, by resort to an established legal fiction, treat the security as subsisting for the purposes of allowing the subrogee to succeed to it and, if need be, enforce it as against the principal debtor. This stands in contradistinction to “simple subrogation”, which involves the succession to rights that have not been extinguished by any prior act or event; the prime example of this is an insurer’s right of subrogation to its assured’s chose(s) in action against third parties: Andrew Burrows, The Law of Restitution (Oxford University Press, 3rd Ed, 2011) (“The Law of Restitution”) at pp 146–147.