I'm a physicist by training. So for the sake of the argument, let's assume someone comes to me and says he has a new theory and wants me to calculate something. From my expertise I can however tell that the theory is meaningless nonsense. So what will I do? Am I being honest and quit the job, or will I play along and deliver meaningless pseudoexpertise?
Smart people know what they don't know, and listen to advice.
Physics is a largely determinate hard science. Hardly comparable with political theory and futures.
There is a distinction between listening to advice, and following advice purely because it is from an expert.
If the adviser is piqued merely because Theresa May won't do what he advises, that is his problem.
I listened to plenty of so called advice from remainers to vote Remain before deciding to vote Leave.
The reason I say so called advice is because much of it was propaganda and full of obvious holes.
So the ambassador should not report on predictions made by Europeans.
Not at all. If an important european such as Angela Merkel clearly makes a relevant prediction, the ambassador may report that fact.
However it is not the job of the ambassador to be making his own predictions, or agreeing or endorsing with others' predictions.
Given that we are not yet a McCarthyist state, denying jobs and opportunities to people based simply on their current or previous political affiliations, no matter how much the Daily Fail and its afficianados would want it, I see this line of enquiry as divisive and barely short of malicious.
The concept that key jobs concerning Leaving the European Union should be given to enthusiastic Remainers
makes about as much sense as nominating an unrepentant Richard Dawkins to be the next Pope.
Besides which the facts here are that:
(i) Sir Ivan Rogers was not entitled to a job for life
(ii) Sir Ivan Rogers chose to resign.
(iii) The Prime Minister is entitled to appoint a replacement who will be enthusiastic about it.