In this Part "Post Office company" means a company that—
is engaged in the provision of post offices,
is or has at any time been—
a subsidiary of the original holding company, or
in the same group as a company that is or (as the case may be) was at that time designated under this section, and
is designated for the purposes of this subsection by order made by the Secretary of State.
A company may be designated only if, immediately before it is designated, it is wholly owned by the Crown.
An order under subsection (1) may not be amended or revoked.
An order under section 93 that appoints a day for the commencement of section 1 (removal of restrictions on ownership of Royal Mail Holdings plc etc) may not be made unless Post Office Limited (registered number 02154540) has been designated under subsection (1).