Inside the Royal Navy's secret submarine factory
"I always say that any day when you don't see a submarine is a day wasted."
Jon Swift loves his subs, that much is clear. For an engineer, they are the ultimate challenge.
"We take a metal tube, put a nuclear reactor in it and a hundred sailors. Then we cram every available space with weapons and hi-tech equipment. Finally, we send it deep into the ocean. Everything has to be safe - and seen to be safe."
Mr Swift is also passionate about his job. Which is at once easy and impossible to describe. Simply put, he is in charge of making seven new nuclear submarines for the Royal Navy.
The actual metal-banging is done by BAE Systems (as well as a vast amount of computer-aided design and hi-tech system installation). 5,000 people work at the company's submarine yard in Barrow-in-Furness, Cumbria.
Royal Navy Engineers work alongside the civilians, ensuring everything is as they want it.
Jon Swift leads a team of 100 who do that very 21st century job: Project Management.
He is based at MoD Abbey Wood, a vast complex of offices perched on the ring road round Bristol's northern fringe. 8,000 people work here, civilians and uniformed people, finding, buying and maintaining every piece of kit used by the armed forces.
Abbey Wood takes a pounding in the media. When soldiers don't get the right kit in the desert, it's the 'pen-pushers of Abbey Wood' who are blamed.
Now Abbey Wood's top brass want to tell their side of the story. Two of us were invited in, to see the projects they are most proud of. First up, submarines.
In some ways it's a surprising story to pick, from an MoD point of view. HMS Astute, the first of the new breed, already has its own archive of news stories. First, there was the unfortunate episode off Skye, when she ran aground in sea trials. Then there was the tragedy in Southampton Docks, when a crewman turned a weapon on an officer.
But Jon Swift is on the front foot. He shows me round the enormous Barrow yard like an enthusiastic small boy with the world's best train set. Above us, the huge boats loom. It is an extraordinary place.
"Abbey Wood is the office," he smiles, "but here's where I come for a dose of engineering. Being part of the submarine programme gives you great pride: the power, the stealth, the sheer complexity."
I have never been in a factory like this.
And with good reason. There is no other factory like this.
No-one else makes nuclear submarines. And that can be a problem.
If Jon Swift and his team don't like what BAE Systems are doing, they can't go anywhere else for their subs. BAE Systems have a monopoly. Of course, he points out, this is also a "monopsony" (now there's a word for scrabble lovers). Jon, and the Royal Navy, is the only customer. Who else buys nuclear submarines?
"It's like a marriage," he explains, "but not one that's going to end in divorce. We work very closely together. I have a team of 30 people here on site, it's all very hands on, eyes on." Unlike a normal business relationship, both sides see each other's numbers. Both sides need this programme to work. And yes, there are low points as well as high points.
Probably the lowest was the day the National Audit Office published the increase in costs. The MoD's original estimate for the first three boats was £2.58bn, but they have come in at £3.8bn, a cool £1,200,000,000 over budget. And that is definitely one of Jon Swift's jobs.
"It's absolutely important that we deliver on time and to cost, but the difficulty with these complex major projects is getting those original estimates right."
It is true that few experts question the final bill. Around a billion pounds for a nuclear sub is "the going rate", one told me. The problem is those early estimates, when ministers want to hear good news, and everyone involved guesses low. Then things get complicated. Jon Swift's team check every increase, but gradually the bill heads north until we have a billion pound overspend.
We stand high in the dockyard now, on a gantry above both submarines. John Swift looks down on them, with affection as well as pride. It is his job to defend the public finances of this project, but also, I realise, to appreciate the engineering.
"The astute class submarine," he smiles, "she's big she's black and she's awesome, and like any primadonna, she's worth waiting for."