LIKE many others, I felt glad when the contract for building the Royal Navy’s new aircraft carrier, the Queen Elizabeth, was awarded to Govan, and the contract for fitting it out to Rosyth. I happened to be in Easter Ross when the ship sailed into Invergordon during her first trials at sea, and a fine sight it made.

Now it has left us for good for its permanent base at Portsmouth. There a different sort of sentiment seems to have overlain the natural pride the craftsmen of Clydeside can take in the completion of their skilled tasks or the instinctive awe we may all feel when, round the rugged coasts of Scotland, the works of mankind are dwarfed by the wonders of nature.

For example, when Theresa May went to welcome the carrier sailing up the Solent, she declared: “Britain can be proud of this ship and what it represents. It sends a clear signal that as Britain forges a new, positive, confident role on the world stage in the years ahead we are determined to remain a fully engaged global power, working closely with our friends and allies around the world.”

Admiral Sir Philip Jones, head of the Royal Navy, waxed no less lyrical: “HMS Queen Elizabeth is the nation’s future flagship, the embodiment of Britain in steel and spirit. In the years and decades to come, she and her sister ship will demonstrate the kind of nation we are – not a diminished nation, withdrawing from the world, but a confident, outward-looking and ambitious nation, with a Royal Navy to match.”

Defence Secretary Sir Michael Fallon added: “Today we welcome our mighty new warship, HMS Queen Elizabeth, to her home for the very first time. She is Britain’s statement to the world: a demonstration of British military power and our commitment to a bigger global role.”

A bigger global role? Now there’s an interesting thought. As a matter of fact, the UK’s global role has been shrinking for more than half a century. While the unmistakable signs of economic weakening had appeared long before, the 1960s saw an agonised debate about the military implications of it. India had only been abandoned a couple of decades earlier. The pain of humiliation at Suez burned still. Now the country was forced from sheer penury to question whether it could keep a presence east of Suez, and soon decided it could not. The US took over as guarantor for the Shah of Iran, or for the Gulf’s sheikhs and emirs, with indeed an offer of basic security to every pro-western government as far as Australia and New Zealand. The Americans soon began to learn some of the same bitter lessons as the British had learned during 150 years of imperial ascendancy.

Today the sole permanent distant presence the Royal Navy maintains is in the Falkland Islands. We do, by way of temporary intervention, join in international operations further east, against piracy off Somalia or in keeping the Gulf as quiet as we can. We train the Iraqi navy, for instance – good luck with that one. But it has all been strictly as part of our contribution to the western alliance, with no British bases occupied and no wider ambitions trumpeted.

Is this now to be changed for the bigger global role? And is it linked, as May and Fallon heavily hint, to Brexit? Funny how nobody seems to have mentioned any such connection before.

In any case the UK is getting one new aircraft carrier but then also a second one, the Prince of Wales, in 2020. This seems to show the Tory government is in earnest about its embellished ambitions. They are expensive commitments, due to cost more than £6 billion in all, when almost every head of public expenditure is being cut in the face of a £56 billion deficit. A curious fact is that the UK will then have more carriers than any other country, with the exception of Italy, which also has two (though half the tonnage of ours), and of the US – which, with 11, has more than all the rest put together.

The possession of an aircraft carrier puts a nation into the premier league of naval powers. It is normally a carrier that acts as the flagship of the entire fleet. This is no doubt why the government in London, having done without one altogether since the last older carrier was scrapped, is anxious to break back into the league with a bang. It is, admittedly, a small league, containing only eight countries altogether. Within it, the UK will have nominal naval superiority over Russia, China, India, France, Spain and Thailand.

Of course, the matter is more complicated than this. President Vladimir Putin has already given another example of his grim wit and wisdom with the quip that the Queen Elizabeth would make good target practice for the Russian air force, and we can expect it to be followed round the oceans by a swarm of his spying aircraft and auxiliary vessels. Being big, and having a flagship’s strategic functions, aircraft carriers are critical assets to any navy and make a tempting target for an enemy if hostilities do break out. The UK lost five of them during the Second World War and, since we depended for survival on naval supremacy, each sinking was seen as a national disaster. But then Japan lost 16 of them, which goes to show the depth of its defeat in that conflict.

The lesson is that one carrier, or even two, will never be enough. With almost the whole deck needed for take-offs, there is a lack of firepower. By themselves the unwieldy carriers are then vulnerable to attack from the air, from other surface vessels and from submarines. Nowadays there are also anti-ship weapons systems which may have rendered them obsolete altogether, in the sense of being too vulnerable for modern combat. This is why they normally get accompanied at sea by other ships to carry supplies, provide protection and give additional offensive capabilities. A carrier can only sail as the centrepiece of a battle group.

It is here that the ambitions of Theresa May and her merry men for a bigger global role still leave something to be desired. At the time of the Falklands War in 1982, the UK had 60 frigates and destroyers. Today the figure is 19 – and the Royal Navy is probably too small even to protect our own shores, let alone engage on its own account in warfare elsewhere. Inevitably, then, the Queen Elizabeth will not be able to operate effectively except as part of somebody else’s fleet, and that can only mean the US fleet. The aircraft carrier sailed into Portsmouth last week, but its real home base will be Norfolk, Virginia. In the spirit of Trump, we will be relieving our American cousins of part of the burden of defending the free world.

The special relationship will be further cemented because the aircraft actually using the new carrier will be of the type F35B, for which the main contractor is the American defence giant Lockheed Martin (though some components are made over here by BAE Systems and Rolls-Royce).

The deck of the Queen Elizabeth will be able to accommodate a couple of dozen of them, because they can perform vertical take-off and landing. Unfortunately the UK can barely afford these technological wonders. They cost, fully equipped, $251 million each – and the pound is sinking against the dollar. For a while, then, the Queen Elizabeth will need to go on its exercises without any planes aboard. A bigger global role is an expensive business.

Especially when the actual operations in which the carrier and its aircraft are likely to engage will be against various oriental despotisms east of Suez, the very region we decided to abandon half a century ago because of its strategic irrelevance to us. But the ragged tribesmen of Afghanistan just hide deep in a cave when a stealth fighter comes calling. Somehow I doubt if we are going to mess with China over the Spratly Islands. Is this the new, confident role on the world stage? It looks more like the last twitches of a dying imperial dinosaur.