Ask any train user, the prices are shocking these days. One day, a first-class King's Cross to Harrogate return might sell for £186, but leave booking too late and you might as well – this must be the royal household's thinking – spend £23,219 travelling by private train.

True, its lead passenger, Prince Charles, made a few detours that would have pushed up the regular price and perhaps confirmed, to anyone but a courtier, that last year's Harrogate expedition might have been better done by car. Failing that, royal progress to York's railway museum might have been broken overnight, an immediate saving, using public transport, of around £20,000.

But as Buckingham Palace demonstrated when it released the latest accounts – with some fanfare about value for money – current royal practice still adheres, perhaps understandably, to strict King Lear (before he went mad) guidelines on retinue and appurtenances.

Reason not the need for the Duke of York to squander £14,692 on a round trip, by chartered plane , to see the golf at Muirfield (true, the Royal Highland Fusiliers also got the benefit of his wisdom). Once the palace accepted that there might be better uses for the £10,559 that this same iconic oaf blew on a return trip to Edinburgh, the whole Mountbatten edifice could be exposed to potentially terminal, Regan-style challenges.

For one would then have to ask why York's fellow dependent, our brother Wessex, needed to take a £46,198 charter flight to Sofia, Bucharest and Ljubljana, with his wife, the former PR, given that nobody outside those destinations and the immediate Wessex family appears to have registered this triumph by some of the world's least promising – no disrespect to Prince Andrew – diplomats. And why 10 days was not enough notice to book Prince Charles on a scheduled flight to Nelson Mandela's funeral, as opposed to a private jet costing £246,160.

Anyway, by way of a comprehensive excuse, a royal spokesperson offered: "Members of the royal family only travel to places because people want them to go there." I think I get it: maybe the public should applaud a modern royal family that is willing to take flights and trains to meet its needs, as opposed to, say, a palanquin or a ceremonial barge.

Yet, for all its defence of velveteen, scented-towelette luxury as the natural state for individuals of the Countess of Wessex's eminence, the royal household does manifest some awareness, however dim, of a public interest that may not forever accept the addition of a strapping male toddler as evidence of superb value for money. It is, they concede – perhaps out of some folk memory of what happened in 1649 – imperative to spend responsibly, bearing in mind the obvious requirement for the Duke of York to be protected from shared lavatory facilities.

A lengthy preface to the latest royal accounts, which featured an increased cost to the taxpayer of 5.7%, to £35.7m (minus figures for security and the lost revenue from the Duchies of Lancaster and Cornwall), stresses how "the different generations of the Royal Family help to make the work of the Monarchy relevant or accessible to people at every stage of life". And it is true, ever since their appearance at the royal wedding, that Princesses Beatrice and Eugenie have been considered a priceless asset by older subjects who still miss the 70s comedy duo, Dr Evadne Hinge and Dame Hilda Bracket.

In a further attempt to finesse its escalating cost, to which the refurbishment of a 20-room apartment for the benefit of an unemployed young family of three made a dramatic contribution, the royal household resorted to its traditional trick for trivialising extravagance: advertising the footling sum that the individual subject notionally pays for, among other things, Prince William's two kitchens, Prince Charles's 2.5 valets and Prince Andrew's numberless recliners with built-in massage function. What kind of ungracious skinflint makes a fuss about 56 pence a year?

In reality, of course, the calculation is fatuous, the true cost of running an extended royal family being multiples of £35.7m , and the number of forced contributors to wee George's rompers and the Duchess of Cambridge's heavily subsidised thongs being 29.9, not 64.1 million taxpayers. But given the widespread readiness to accept the palace maths and the role of a surging population in making such figures ever more impressive (yet more so when converted into units of popular confectionery), it is remarkable, really, that many unpopular public expenses are not similarly disguised.

The £1.7m cost of deporting Abu Qatada, for example, looks like incredible value once you divide it by 64.1 million; ditto the annual cost of bariatric surgery if you measure it in individual Rolo portions, not nurses, and the hugely resented MPs' expenses, which last year totalled £100m. My stab at a palace-style calculation brings the last figure down to around £1.53 per head, significantly less than a 100g bag of Percy Pigs, and with the bonus, in the case of the public servants, of being able to throw them out if they spend it all on trains.

By way of further reassurance, an underling told journalists, William's refurb was "done to a very comfortable but ordinary level… I think you might all feel at home in it". We're clearly talking a lot of spittoons, then. In another ambitious attempt at demotic solidarity, the speaker invoked, to the best of his ability, the bank of mum and dad: "Young couples setting up home receive some help from their parents or grandparents." The only serious difference, you gather, being that most parents have to spend our own money on our children's palaces, as opposed to drawing, as in Charles's case, on the £19.5m income from a state asset, the Duchy of Cornwall, a property widely and erroneously believed to be his own.

As for Charles's profligacy, you might as well ask Kubla Khan why he a stately pleasure-dome decreed. "The Prince of Wales lives the life of the heir to the throne," a courtier said. "He lives in London in a royal palace and has staff who enable him to do the job that he and her Royal Highness have created for themselves."

This superb condescension, far more revealing than a sketchy summary of accounts, suggests a royal household whose character is already less redolent of the restraint and Tupperware associated with the current monarch than of her heir's evident conviction of his own, semi-divine exceptionalism. Niggling questions of a monetary nature cannot be allowed to burden this authority on every aspect of political, aesthetic, environmental, physical and spiritual life, whose worldly requirements, from private trains to immaculately boiled eggs, nonetheless transcend all the usual constraints of sensitivity and proportion.

All to the good. Today's Roundheads are depending on Prince Charles in much the same way that Cameron prays every night for the preservation of Ed Miliband. But 56p each is still 56p each too much.