The rules only matter with regard to who's allowed entry under what status. They're not subject to review after entering, except for expulsion.
I'm going to assume you're conflating the definitions of diplomat. The Vienna convention only sets a minimum standard. The things you're taking about might matter if it's the US and maybe Libya.
For friendly countries, there are agreements that extend the diplomatic privileges well beyond the core diplomatic party.
And once rules are agreed upon, they only apply to who is let into the country under what status. So entry can be denied, but once allowed in with a diplomatic or official passport, the host country can't change that status. All they can do is expel the person.
If the UK allowed entry under a diplomatic / official passport, that's all that matters.
Regardless, in a "possession is 9/10s if the law" sort of way, the only thing that matters in practice is if the visiting country waives immunity.
The rules only matter with regard to who's allowed entry under what status. They're not subject to review after entering, except for expulsion.
I'm going to assume you're conflating the definitions of diplomat. The Vienna convention only sets a minimum standard. The things you're taking about might matter if it's the US and maybe Libya.
For friendly countries, there are agreements that extend the diplomatic privileges well beyond the core diplomatic party.
And once rules are agreed upon, they only apply to who is let into the country under what status. So entry can be denied, but once allowed in with a diplomatic or official passport, the host country can't change that status. All they can do is expel the person.
If the UK allowed entry under a diplomatic / official passport, that's all that matters.
Regardless, in a "possession is 9/10s if the law" sort of way, the only thing that matters in practice is if the visiting country waives immunity.