What the law says
For a debt to extinguish after 20 years, specific criteria must be met. Section 7 of the Prescription and Limitation Act 1973 outlines the following.
7.Extinction of obligations by prescriptive periods of twenty years
(1) If, after the date when any obligation to which this section applies has become enforceable, the obligation has subsisted for a continuous period of twenty years–
(a) without any relevant claim having been made in relation to the obligation, and
(b) without the subsistence of the obligation having been relevantly acknowledged,
then as from the expiration of that period the obligation shall be extinguished:
Provided that in its application to an obligation under a bill of exchange or a promissory note this subsection shall have effect as if paragraph (b) thereof were omitted.