Our reporter Richard Jones has followed the development of the navy's new aircraft carriers since they were first proposed 20 years ago. For the last few years he's followed the progress of HMS Queen Elizabeth's construction. Here's his personal view.
Seeing is believing.
That's what I tell people when they ask me about the Royal Navy's new carriers.
For years she's been out of sight and to a degree out of mind. Construction has been taking place at the Rosyth Shipyard on the Forth in Scotland.
That means few people have been able to follow her progress and that's probably why there's been so much scepticism about HMS Queen Elizabeth and her sister ship Prince of Wales.
In addition they went over badly over budget, their cost increasing from £4 billion to more than £6 billion. Lack of cash meant the production process was slowed down. There was even talk that one of them would be built and then mothballed or sold.
"Oh, are they actually happening?," someone said to me the other day as news of HMS Queen Elizabeth's arrival in Portsmouth was announced.
Yes, they are happening. I know because I've been aboard Queen Elizabeth, I've seen her close-up, I've met her crew, and I've spoken to her Captain.
And yes she is huge. More importantly she's a feat of British engineering excellence. And her crew have risen to the challenge of getting a brand new ship ready for sea.
I first filmed the carrier back in 2012 when sections of her were being built at the BAE Shipyard in Portsmouth. Over the next two years a key section of her hull and the forward island for her flight deck were transported by barge from the south coast to Scotland.
I got my first chance to visit the ship in Scotland shortly before she was named by the Queen in July 2014. Even then there was great excitement among the small number of crew attached to the ship.
"It's hugely exciting," the then senior naval officer aboard Captain Simon Petitt told me. "I've got 100 sailors working for me and all of them are hugely proud to be connected with HMS Queen Elizabeth. It's exciting, it's novel, it's new. Everyone wants to be at the birth of a new ship."
But there were still years of construction ahead. Again the Queen Elizabeth slipped out of public consciousness. There was yet more criticism. There were issues with the F35s due to fly from her. They'll be late into service meaning she's been dubbed the aircraft carrier with no aircraft.But on two further visits to the ship in 2015 and 2016 I saw her being transformed from a building site into a ship. Progress was quick.
"The ship already has its own identity," one of the crew told me. "The crew are here to give it soul."
The following year almost all of Queen Elizabeth's 600 crew were based in Rosyth, working from an office building near the ship.
"We've got a bit of work going on today," said Leading Engineer Aled Jones. "But in the coming weeks and months we should be done and ready to go."Shortly afterwards Queen Elizabeth's first CO was appointed. Captain Jerry Kyd, who's from Hampshire and studied at Southampton University, is one of the navy's brightest talents.
"We're moving from a period of ship build and now we're looking forward to taking her to sea," he told me just after taking charge. "The important thing is to get this ship operational as fast as we can. Let's learn how to use this amazing ship, find out its strengths, the areas we need to work on, get her to sea, get her through sea trials, and get here down to Portsmouth and join the fleet."
Back in Portsmouth there was work going on to get the naval base ready for the carriers. A refurbished jetty, new navigation lights, a power station, £100million was spent. Again most of it was out of sight, except when the dredging of a deeper channel into the harbour uncovered wartime bombs which had to be blown up.Then on June 27 this year HMS Queen Elizabeth set sail for the first time. She left the dock at Rosyth, headed under the Forth Road bridge, and out into the open sea.
She was expected to arrive in Portsmouth later in the year. But her initial sea trials went well and the decision was taken to head to her new home port sooner rather than later.
There are more sea trials ahead - the ship won't actually be handed over to the Royal Navy until December.
But her arrival in her home port will be a major milestone. For the first time people will be able see see her for real and judge just how big she is. Seeing will be believing.