For all you ill-informed journos and bleaters out there, this is how it works:
A Sqn is allocated a certain number of trg hours per month / year / etc. Those hours are already accounted for within budgets.
ALL sorties have to be authorised in writing, stating the legitimate reason for the flight taking place. You cannot just 'take' an aircraft on a jolly, and there is no 'fig leaf' covering possible. You cannot LEGALLY fly without a proper and correct authorisation.
This sortie would have gone ahead in any case, whether HRH was on it or not. It may have used different destinations for its training purposes, it may have gone to the same places, who knows - that is entirely down to what the crew needed to achieve from THEIR trg hours.
Therefore the supposed cost to the taxpayer of this 'jaunt' is ZERO, as it ALWAYS IS with things of this nature. If it incurred costs outside of what had already been paid for (ie the trg hours) we would not be able to do it!
Just what is it about this that you don't get?
BTW, Jacko, I'm truly surprised at you. You're normally much more clued up about how we go about our business!