Sch 1A para 6
The fifth condition is that— (a) the trustees of a trust or the members of a firm that, under the law by which it is governed, is not a legal person meet any of the other specified conditions (in their capacity as such) in relation to company Y, or would do so if they were individuals, and (b) X has the right to exercise, or actually exercises, significant influence or control over the activities of that trust or firm.