Penny Mordaunt is a former Defence Minister and is MP for Portsmouth North.

“I fear we have lost the carriers. Both”

That was the dread update given to me by a minister in the 2010 coalition government, halfway through the Strategic Defence and Security Review (SDSR).

My first campaign in Parliament, working with others, was to ensure we had both ships, for without both we would not have the assurance of one available at all times. The campaign was successful and to their great credit, and despite Labour’s legacy of a black hole in the defence budget that was twice the size of the defence budget, Liam Fox and the Service Chiefs gave the green light to both ships.

They were right to. When our nation has had carriers they have been busy, utilised in every humanitarian crisis and conflict situation you care to name, and, for every such situation you can name, there will be dozens more that were pre-empted by the influence and deterrence a carrier brings.

As well as the reach, offensive power, and versatility of big decks and fast jets, it is perhaps their ability to alter events and prevent conflict that gives us the best return on investment. They are a big stick which enables us to speak softly.

And when you consider that previous carriers could fit very comfortably on HMS Queen Elizabeth’s flight deck, I’m talking about a very big stick indeed. She will dwarf Portsmouth’s shoreline as she enters her home port for the first time today.

It will be an awesome sight, and I will have a lump I my throat: I campaigned to secure her; I’ve clambered through her many sections in Portsmouth and Rosyth; was there when steel was cut; when she was named; and met many of her crew and support staff as they have trained and maintained that capability.

I feel such a connection to her, and I know I am not alone in feeling that way. There is not a place in the UK which has not contributed to her generation, so vast is the supply chain of one of the most complex engineering projects our country has ever undertaken. All who have contributed to that moment should be immensely proud, as should our nation be of this remarkable ship and those who sail her.

As well as the goosebumps some will feel, all should understand that her commission marks more than just the return of credible maritime force. She is a powerful metaphor for national endeavour and confidence. A symbol of our global ambition, her timing perfect as we are set to expand our trading opportunities across the globe. She has delivered unprecedented inter-operability with our closest ally, but also marks our resolve that, if need be, we will act alone to protect the UK’s interests.

She is the perfect illustration of both the breadth of effect defence provides and its purpose. In that one capability the whole story is told: our dependence on sea freight (90 per cent); the need of sea control; the ability to influence; to aid; to deter; to intervene; and to strike. The mission, doctrine, effort, and means explicit in 70,000 tonnes of steel.

The national focus on this great ship affords us the chance to reconnect the public with the forces that defend them. In recent times that connection has been weakened, often only seen through the prism of care and concern for casualties of conflicts, whose relevance to our national security and interests has been, in the public’s eyes, at best, vague.

Post-Iraq and Afghanistan the public favoured non-intervention, yet still loathed the impotence they felt as they watched barbaric acts against innocent civilians, or escalating threats and hostility from those who would do us harm, played out on their TV screens. They want us to have options to protect our interests, and for us to use them well.

At this time it is not just the case for sound money that needs to be made over again, but also the case for strong defence. We must seize the opportunity the new carrier brings to do that. For without strong public support, strong defence is not possible. For all those who campaign to ensure our national security, the carriers are a foothold that the ambitions of the 2015 SDSR will be realised.

In the challenges that lie ahead and the decisions that accompany them – on the shape and size of the frigate fleet, on carrier support and aviation, and more – we would do well to follow the example of another Queen Elizabeth.  Under her leadership naval investment was maintained, and capabilities consolidated and maximised.

She understood that her kingdom depended upon credible and constant sea power, just as the UK does today. It is appropriate that HMS Queen Elizabeth, named after our current sovereign, will bear the motto of her namesake predecessor: Semper Eadem.

We are, and always will be, a maritime nation.