It is the UK's biggest ever warship at 65,000 tonnes and took more than 10,000 people to build.

The sight of admiring bystanders at the launch of Britain's new aircraft carrier in Rosyth, including the Queen, Prime Minister and First Minister, called to mind images of Scotland's great shipbuilding past when vast ocean-going liners like the Campania and the Lucania, then the fastest and largest in the world, were launched on the Clyde.

The Queen Elizabeth is an awesome vessel that is rightly regarded with pride by those who built it, but it has swallowed up a huge chunk of the defence budget, coming in at £6.2 billion, three times the original projected cost. The overspend has understandably prompted criticism at a time of defence cuts and job losses.

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The project's defenders say it will offer improved capabilities in war, in delivering humanitarian aid and disaster relief and, to quote Defence Minister Philip Hammond, enhance "our ability to project power anywhere in the world". That shows the UK Government has not lost its appetite in a rapidly changing geopolitical landscape for being perceived as a major military power but it is not an argument that will impress everyone.

Critics argue the plans are too ambitious, pointing to the vastly expensive Lightning II stealth aircraft, due to use the carrier, that have experienced various technical problems; at the same time, there is doubt over the future of a second aircraft carrier that might not even be used by the Royal Navy. But the immediate concern for Scottish shipyard workers is: where will their work come from in future?

The referendum debate looms large thanks to rumours that the UK Government would not want Royal Navy ships to be built in Scotland in the event of independence, and fears that an independent Scotland would have neither the need for many ships nor the money to spend on them.

A final decision on plans for a fleet of Type 26 frigates to be built at Scotstoun in Glasgow (which would undergo a £200 million upgrade for the purpose) is being held off until after the referendum. In reality, given that the expertise and facilities within the UK for building such ships are concentrated on the Clyde, the frigates might still be built there regardless of the vote's outcome. What future the yards would face after the frigates, however, is another matter.

There is no knowing what the requirements of the British, or Scottish, navies might be in 20 years' time and, therefore, there have long been calls for new opportunities to be found for Scotland's skilled shipbuilders. Diversification into civilian or merchant navy vessels, or indeed new areas of marine engineering, might provide Clyde shipworkers with a long-term future, though it may take the emergence of a visionary entrepreneur to kick-start such a new chapter.

What is beyond doubt is that Scotland's expertise in this area is a huge asset, and maintaining and building on it must be a priority for any government.