It doesn't altogether answer your question, but in setting up a new non-profit (potentially charitable) organisation, we're looking at making the council a director. This assumes that the organisation is a company limited by guarantee. A corporate body can be a director of a company. I don't know whether a similar approach can be applied to a non incorporated trust. The advantage of this approach is that the council obviously has to be represented by a councillor in practice, but the councillor is never appointed a trustee as such. Thus, if the person ceases to be a councillor, they automatically lose the right to act on behalf of the council. The council remains a trustee and has the right to nominate a new representative. The aim is to avoid the common situations where either an individual remains a trustee and the council forgets to exercise its right to appoint a new trustee, or the trust falls into a state where the trustees are dead or incapable of acting.