UPDATE I find people need more explanation than I realised. The UK is bound by a common position under EU common foreign policy (third pillar). So until Brexit the official line must still be always given that the UK is not considering moving its Embassy. Post Brexit that restriction is lifted. What my source is saying is that secret contingency planning for a post Brexit move to Jerusalem is underway in the FCO. What I have been pressing the FCO for is an admission that planning is taking place. Obviously this is not something they would want to be public knowledge at present.
My source stated that the move is partly ideological, and partly to sweeten relationships with the USA in seeking a trade deal. My own observation is that the Tories probably think this would cause more trouble between Corbyn and the Parliamentary Labour Party, and that the Westminster classes are totally out of touch with real public opinion on Palestine, as they seldom meet anybody who does not share their extreme zionism.
This information about planning being carried out in great secrecy came to me from an FCO source I had no previous contact with, so I do not know the reliability. It might even be a hoax to make me look foolish. Therefore I decided to check the story with the FCO Press Department, but I can’t get any response out of them. Not answering questions appears to be the standard British state response to independent journalists now. If this is nonsense, it would have taken the FCO two minutes just to tell me so.
So I am posting this here with the caveat that the information is not verified yet. There is much to be said on motive, both from what I was told by the source and from my own gloss, but I shall leave that until we can make more progress on validation. Obviously, I hope the posting may spur the FCO to respond, or others to corroborate the leak.