In Smithson v Hamilton, the Court of Appeal held that a compromise agreement which treated particular scheme rules as "avoided" was for the benefit of everybody who was represented by certain representation orders.
It was common ground amongst the parties that a rule which provided that a deferred member who had reached age 60 could retire on an unreduced pension was a mistake. The original claim was not for rectification; instead, broadly, the claimant attempted to have the rule declared void on the grounds of mistake (by application of the so-called Hastings-Bass principle). This claim was rejected but the parties reached a compromise agreement under which certain scheme rules were to be "treated as being avoided".
Unfortunately, the detail remains confidential so it is not possible to draw many conclusions on the application of the principles of rectification or the doctrine of mistake. However, on a procedural point, it is worth noting that the court ruled that the compromise agreement only became binding 28 days after the affected members were sent letters notifying them of the compromise, and, hence, given an opportunity to make any relevant applications to the court.