(a)a person who at the time of the alleged offence is a Head of State, a member of a body which performs the functions of Head of State under the constitution of the State, a Head of Government or a Minister for Foreign Affairs and is outside the territory of the State in which he holds office;
(b)a person who at the time of the alleged offence is a representative or an offical of a State or an offical or agent of an international organisation of an intergovernmental character, is entitled under international law to special protection from attack on his person, freedom or dignity and does not fall within the preceding paragraph;
(c)a person who at the time of the alleged offence is a member of the family of another person mentioned in either of the preceding paragraphs and—
(i)if the other person is mentioned in paragraph (a) above, is accompanying him,
(ii)if the other person is mentioned in paragraph (b) above, is a member of his household;
This is from the 1978 Internationally Protected Persons Act.
As Harry is no longer a working royal he wouldn't qualify under sections (a) and (b). He might not have qualified anyway.
He is a member of KC'S family, though, so might get protected under that. Except he never accompanies KC nor is he any longer a member of his household.
So I don't see how he could qualify for IPP status. Is he actually looking for that? Or just the right to pay for 24hr armed protection for him and his family when he comes to the UK?