Michael Cockerell behind the scenes with the Tory Leader
David Cameron is a child of the media. He spent much of his early career as a PR man for a TV company and advising top Tories on presentation.
Most politicians become leader and then get themselves a spin doctor. Cameron went from spinning to leading.
And since then he regularly talks direct to camera for his internet site, Webcameron.
So he naturally tends to second guess anyone who wants to make a film about him.
Many a modern political leader's public appearances are specifically moulded for the media - with the moulding process strictly off camera.
And the danger of doing a William Hague in a baseball cap, or a Neil Kinnock in the waves, is never far from the thoughts of leader and his minders.
Mr Cameron has tried to create a new image for his party
We decided to take Cameron's two years as leader as our canvas. Unconsciously he had already given us our title.
When he grabbed the leadership as the outsider with his famous speech at the Conservative conference at Blackpool in 2005 - he had told the party faithful: "Come with me it will be an incredible journey."
He turned out to be right: it has been a remarkable rollercoaster ride for Cameron and his camera-shy media guru, Steve Hilton.
"Steve is a pint-sized Rasputin who is never far from Dave's side," says Tara Hamilton-Miller, who knows Cameron and Hilton well from working with them in Conservative party HQ.
The two men modelled their transformation of the Tory party on the Blair/Mandelson/Campbell blue-print for New Labour.
Hilton and Cameron agreed that if the Tories were to win back power - everything about the party would have to change; and Cameron himself would be the iconic symbol of that change.
'Vote blue, go green'
To attract mainstream voters, he deliberately stopped talking about traditional Tory issues - like immigration, Europe and cutting taxes - and he started talking about education and health and especially the environment.
Hilton came up with a classic political rebranding slogan: 'Vote blue, go green'.
Camera shy: Steve Hilton is Mr Cameron's closest adviser
The Tory leader and his spinmeister used the most graphic images to get their message across: hence hug-a-huskie and hug-a-hoodie.
But last summer everything suddenly went belly up for Cameron. If something possibly could go wrong for the Tory Leader it did.
And it was accompanied by a bravura performance from the new PM, Gordon Brown
At Prime Minister's Questions, Brown declared. "The wheels are going off the Tory bicycle. And it is just as well he has got a car following him when he goes out on his ride."
Labour MPs took to texting each other PODWAS - Poor old Dave what a shame.
Mr Cameron faced pressure from Tory traditionalists
They were joined by the Tory press along with some Conservative grandees and MPs, who said that if Cameron didn't get his act together - he would have to go.
As Brown and Cameron faced their party conferences last September - it looked as if the Tory leader's incredible journey was about to end in a horrible train crash.
It seemed that Brown, who was over 10% ahead in the opinion polls, was about to call a snap election - with a Labour landslide predicted.
Cameron knew that he had to make the speech of a lifetime to give the Tories a bounce in the polls and make Brown think again about the election.
Team Cameron worked round the clock on the leader's speech.
He took the risky decision that he would make it wandering around the stage without a script or autocue.
A single speech transformed the party's fortunes
Cameron also had another unlikely secret for oratorical success: he had picked it up from watching a film I made ten years ago about the best Tory public speaker of his time - Enoch Powell.
I said to Powell that I had heard he always liked to make a big speech on a full bladder: "Absolutely", he replied, "you should do nothing to decrease the tension before making a big speech - if anything you should seek to increase it."
Cameron specifically refrained from using the loo before going onto the stage make his hour long speech.
The speech was seen as a triumph.
With the polls showing the Tories bouncing back sharply after their conference, Brown suddenly called off the election.
Since then the prime minister's popularity has been going South as fast as the Tory leader's has been rising.
David Cameron is now the longest serving of the three main party leaders.
The environment has been a key theme of Cameron's leadership
As he has watched the changing of the guard at No 10, he has seen close-up how formidable the pressures and demands of the job of prime minister can be.
I asked Cameron whether he had any doubts about his ability to fulfil the role of prime minister
"If I'd had major doubts", Cameron replied, "I wouldn't have put myself forward to lead my party in the first place."
"You have got to be absolutely ready to take the big decisions you would have to take as prime minister, including sending troops to war.
"And if anything after two years I feel more ready today than I did then."
Michael Cockerell's film, Dave Cameron's Incredible Journey, is on BBC2 on Thursday, 20 December at 1900GMT.