Ending a IPDI using Saunders v Vautier

We have an IPDI where son has an interest to receive the income for life subject thereto to his children absolutely. There is an overriding power of appointment the trustees may exercise in favour of discretionary class of beneficiaries some of whom may not even be yet born or ever be born. This has not yet been exercised. Can the son and children exercise their right assuming sui juris to terminate the trust now or does the discretionary power negate the principle in Saunders v Vautier?

Elisabeth Whybrow
Silks Solicitors

The trust cannot be terminated without a release or irrevocable exercise of the power of appointment

Simon Northcott