Two golden rules of royal weddings. First, it’s always wonderful on the day. Second, there is always an almighty official spat beforehand which no one saw coming. When Prince Charles married Lady Diana Spencer, there was a Spanish boycott because the honeymoon included Gibraltar. In 2011, Prince William’s marriage plans had a crisis moment when it turned out the guest list had included the Syrian ambassador but not ex-PMs Blair and Brown.
We can already spot one sensitive issue. Should Donald Trump be invited? For: the bride is American. Against: she backed Hillary. In fact, Mr Trump is unlikely to be invited because he is not a friend and this is not a state occasion. Prince Harry is only fifth in line to the throne and falls further with each new royal arrival at the Lindo Wing.
But don’t rule out a presidential presence. Prince Harry’s greatest achievement is his Invictus Games. Two great supporters have been the previous occupants of the White House. It may displease the Donald, but look out for the Obamas at St George’s Chapel.
This is an extract from Robert Hardman's Diary, which appears in this week's Spectator