The trustees of land shall in the exercise of any function relating to land subject to the trust—
so far as practicable, consult the beneficiaries of full age and beneficially entitled to an interest in possession in the land, and
so far as consistent with the general interest of the trust, give effect to the wishes of those beneficiaries, or (in case of dispute) of the majority (according to the value of their combined interests).
Subsection (1) does not apply—
in relation to a trust created by a disposition in so far as provision that it does not apply is made by the disposition,
in relation to a trust created or arising under a will made before the commencement of this Act, or
in relation to the exercise of the power mentioned in section 6(2).
Subsection (1) does not apply to a trust created before the commencement of this Act by a disposition, or a trust created after that commencement by reference to such a trust, unless provision to the effect that it is to apply is made by a deed executed—
in a case in which the trust was created by one person and he is of full capacity, by that person, or
in a case in which the trust was created by more than one person, by such of the persons who created the trust as are alive and of full capacity.
A deed executed for the purposes of subsection (3) is irrevocable.