I am not sure this is the case. We don’t have a constitution where things like this are all written down. Her Majesty generally tries to do her duty, but this will challenge the system. She may be ‘indisposed’ (feeling sick at the thought of meeting him), or something like that.
Personally, I am rooting for a “GUARDS, SEIZE HIM!” moment.
Indeed, which is why we get constitutional crises when someone wants to do something which isn’t technically illegal but goes against “convention” (like Edward VIII wanting to marry a divorcee).
I suspect that depends on whether he wants to meet her or not. If he does, we’ll no doubt make that happen. Have to placate the only possible source of any ‘good news’ on post-Brexit trade deals…
Not that there will be any reciprocation since Trump will do whatever Trump wants at the time it occurs to him. As he’s repeatedly said he will. I mean it’s not like he tries to hide how he operates.
OTOH, you can bet there is some idiot somewhere in the civil service who will suggest that a meeting with Brenda will allow her to charm Trump. And to be fair she’s probably the person involved in UK government who has the most experience of shmoozing and placating obstreporous foreign leaders. May’s certainly not going to get anywhere with Trump, nor is Boris.
Having the Supreme governor of the Church of England wanting to marry a double divorcee, which was against CofE doctrine until 2002, was a big part of it.