(6)If at any time the party which is the largest political party of the largest political designation is not the largest political party—
(a)any nomination to be made at that time under section 16A(4) or 16B(4) shall instead be made by the nominating officer of the largest political party; and
(b)any nomination to be made at that time under section 16A(5) or 16B(5) shall instead be made by the nominating officer of the largest political party of the largest political designation.
I think this clears it up:
(6)If at any time the party which is the largest political party of the largest political designation is not the largest political party—
(a)any nomination to be made at that time under section 16A(4) or 16B(4) shall instead be made by the nominating officer of the largest political party; and
(b)any nomination to be made at that time under section 16A(5) or 16B(5) shall instead be made by the nominating officer of the largest political party of the largest political designation.
Conal.