Imagine what Donald Trump might say when he gets safely back to the White House after the first state visit to the United Kingdom as President Trump. Having been the guest of the Queen at Buckingham Palace – which we know to have its rough edges - he could take to Twitter to declare:

“Sure, it was grand, but when you looked closely it was decrepit, really it was, a bit like England. Jesus, the john even leaked. #Notsmart.”

Or he could Tweet:

“Let me tell you, it is a beautiful, beautiful place. We were honoured to be there. England is a great, great country. Ivanka loved it. #tradedeal.”

I think we know which we would all prefer. The cost of doing up the Palace, around £369m, is, oddly, about the same amount of money that the Brexiteers said would be available for the NHS rather than the EU budget if we left the European Union. It is also, in the big scheme of things, a fairly modest sum, and in fact represents the bill for a decade’s worth of repairs and refurbishment. So, about £35m a year.

Yes, you could spend it on a new hospital. But if a smartened-up Buckingham Palace helps secure a trade deal with America – and one that could in due course develop into a deeper and more fruitful wider economic partnership – it would be a price worth paying. Even by the taxpayer.

Looked at in that sense, we might also reconsider the new Royal Yacht, which also did its bit for British trade and diplomacy in places where such symbols and craftsmanship are appreciated. Just as the old yacht was state-of-the-art in the 1950s, so the new one could also be blessed with the latest in British technology and traditional craftsmanship.

Queen should 'consider' contributing to palace repair

It could be a superb marketing tool, with its new Rolls-Royce marine engines. A Mini, a Bentley, a Nissan Qashqai, Range Rover, Vauxhall Astra and Toyota Auris Hybrid could be permanently represented on deck in the floating car showroom. Prince Andrew could show those the Arab potentates and Chinese plutocrats the best of British. The guest suites could be stocked to the gunnels with the best Scotch, Mars bars and Marmite. Complimentary.

The yacht, though, is more a matter of choice for the nation; the palace is an imperative. It would only take a few decently-sized arms deals for all the restoration work on Buck House to pay for itself, and for the hard-pressed taxpayer to see a handsome return in investment, jobs and export earnings – which we will need more than ever post-Brexit. Then we can have some new hospitals.

But why shouldn’t the Queen pay? She is, after all, like Donald Trump, personally very wealthy. Well, for one thing, it would be like asking Trump (who can afford it) or Barack Obama (who could not) to do up the White House. Buckingham Palace is like St Paul’s Cathedral or Westminster: monuments of global significance that someone has got to keep in reasonable condition. The fact is that successive governments and keepers of the royal finances have skimped on maintenance for decades, and that is why the bills have mounted up.

As it happens, I think the distinction between the Queen’s “personal” wealth and income, on the one hand, and what is the property and responsibility of the taxpayer, on the other, a rather bogus one. The paintings or the stamp collection or some of the royal homes, such as Sandringham, conventionally regarded as “personal”, could not possibly be sold and the proceeds used for personal consumption by members of the royal family.

Queen's properties from throughout her reign Show all 7 1 /7 Queen's properties from throughout her reign Queen's properties from throughout her reign 1. Buckingham Palace Getty Queen's properties from throughout her reign 2. Windsor Castle Getty Queen's properties from throughout her reign 3. Sandringham Palace Corbis Queen's properties from throughout her reign 4. Balmoral Castle Rex Queen's properties from throughout her reign 5. Palace of Holyroodhouse Getty Queen's properties from throughout her reign 6. Hillsborough Castle Rex Queen's properties from throughout her reign 7. Delnadamph Lodge Creative Commons

They came into the hands of the royal family, directly or indirectly, through the monarch’s position as the head of state with a state income and, for a long time, no tax bills. The same goes for the Prince of Wales’ Duchy of Cornwall holdings of land, properties and financial assets. He couldn’t sell up and retire even if he wanted to. We discovered this when Edward VIII abdicated in 1936, and, apart from some jewellery he had bought for Wallis and a couple of flash American cars, found himself more or less skint on his own account.