This is the photograph board in the Foreign Office security room, used to help guards recognise ministers and assorted VIPs. Eagle-eyed co-conspirators at this weekend’s Open House London event spotted a distinctive black mark above Sir Alan Duncan’s top lip. As an eye-witness explains: “The security guards had clearly biro-ed a Hitler moustache onto the picture of Alan Duncan.” The guards have obviously had the pleasure of meeting Sir Alan. One’s a short, self-obsessed, megalomaniac, the other…