Letter to the Editor: Dominance of Brexit not good for EU
It is difficult to imagine a more insulting act by a head of government than to send a formal letter on headed notepaper purporting to come from his office and person, but omitting to sign it as a means of authenticating it. And then to send another signed letter saying something quite different.
It is the very essence of duplicity. You are either a democrat taking full responsibility for the acts of your office as mandated by your law and parliament or you are a worthless and untrustworthy operator. In declining to respond anytime soon, the EU is actually acting with great restraint. It could have returned the unsigned letter to sender requesting due authentication by signature.