There was a time when pictures of Britain’s most powerful warships lying at anchor at their home port of Portsmouth after undertaking hazardous missions on the high seas would be marked by an outpouring of national pride.

For a nation whose prosperity depends on its ability to trade freely around the world, the ability to maintain a first-class navy is seen as being a vital national asset.

This is part of the rationale that lies behind the government’s decision to build two new Queen Elizabeth-class aircraft carriers – the largest ships ever built for the Royal Navy – which, when they start to enter service towards the end of this decade, will restore Britain’s position as one of the world’s leading maritime powers.