So it is!
251.—(1) A public company whose shares, or any class of whose shares, are listed need not, in such cases as may be specified by regulations made by the Secretary of State, and provided any conditions so specified are complied with, send copies of the documents referred to in section 238(1) to members of the company, but may instead send them a summary financial statement. (Companies Act 1989)
So we assume that TDiplc is a public limited company as defined by the Act