Err...can I come in?

I've posted before about the very real difference between the city of London and the City of London (see 18/5/16).  One fascinating fact is that the Queen has to have permission to enter the City.  It all goes back to her namesake Elizabeth I, and today it's more of a tradition than a rule, but she will still stop at Temple Bar (the entrance to the City) and await the Lord Mayor's invitation before entering.