As someone who's worked on the railways, the quote about the use of the Royal train causing 'minimal disruption' (while costing around £20,000 per trip) stands out to me.
Trains normally run with each train occupying one 'sector' of the line. However the Royal train occupies three 'sectors' because the rules state that there must be a clear sector both ahead of and behind it. That causes massive disruption to rail traffic!
For example, I saw a Royal train come through the station I worked at during the mid-morning period. Trains on that line, and on associated branch lines, were knocked out of schedule for over ten hours aftterwards, causing massive inconvenience to tens of thousands of passengers.
A chaffeur-driven car might have taken an extra half an hour for the journey but, it seems, it was perfectly acceptable to alleviate that small delay by costing the tax-paper a great deal of money and delaying the journeys of vast numbers of rail passengers!