Trustees, etc
The company (as a corporate entity) may be the sole trustee or there may be individual trustees or both. If the company is the only trustee and it goes bust, then the liquidator becomes the trustee. If all the individual trustees die or disappear, then the trust deed of the scheme will set out who has the right to appoint new trustees. At the end of the day, afaik the Pensions Board can apply to the courts to appoint new trustees if no one else will.
In any case, irrespective of who the trustees are, the assets of the scheme are separate from those of the employer. If the employer does under, the money in the scheme is still there and cannot be got at by the creditors. In this situation as in every other, the trustees have a legal obligation to use the assets of the scheme to provide the benefits set out in the scheme rules: even if the liquidator is the trustee, he cannot refuse to pay benefits or hold out for some share of the assets.
By the way, I am not a lawyer.
d