Some of the figures for security seem to be based on a claim that security for the Cambridge's wedding was also around £30m, however according to the BBC report an FoI request showed it was only around £6.35m. I really have no idea, and as the police are neither confirming nor denying it I suspect no one else does. The journalists are probably all copying each other's homework.

The other question is whether this is net or gross cost. The police, army, security services will all be paid their normal salary whatever they are doing, so it is only the additional costs - overtime, travel and specific additional security measures - which should be counted.

Either way, it's likely to have been a lot of money, but these are the times we live in. Even so the income from the Crown Estate makes up for it.