I suspect that our own dear Queen is in a bit of a quandry at the moment, to say the least. (Has any other "head of state", when invited to meet the Queen for a formal state visit in her own country, announced that they will bring along half a dozen members of their family? Could Trump be any more crass?) I think Harry will simply do what is expected of him (by the Queen) which probably means just turning up, taking very much of a back seat, then legging it as soon as is politely possible!
Favourite small treat when feeling blue or conversely a bit flush

