As Gordon Brown continues to fumble, thoughts are turning (again) to Alan Johnson, the Blairite health secretary who increasingly seems like a stronger alternative than the awfully young and perhaps overly intellectual David Miliband. Last fall, The Economist painted a glowing portrait of Johnson.

What makes Mr Johnson formidable is a combination of rare political talent, genuine affability and a back-story that, in Labour terms, is to die for. Few contemporary politicians can have had a tougher start in life. His father, a decorator, ran off when he was eight and his mother, a cleaner, died four years later. Thanks to the care of his 15-year-old sister, he avoided being sent to a Barnardo home, but he left school at 15 without a single qualification. After stacking shelves for a while at Tesco, he became a postman in Slough at 18. By then he was already married with two children.

In his late 30s, with a reputation as a stroppy militant, he was appointed a full-time official of the postal-workers’ union.

But strangely, he became an enthusiastic backer of Blair’s modernizing efforts.

Mr Blair can be a little thespian for some tastes, but Mr Johnson always manages to sound like a normal human being, even when dealing with the most complex and thorny issues.

Of course, Johnson made a number of missteps in the months that followed, and as James Forsyth notes, he discounted his own suitability for the top job.

“I don’t think I’ve got the capabilities. You get to a level and look around and think ‘Perhaps I could go to the next level’. I don’t think I could go to that level, which is the only level up from being a cabinet minister.”

But, well, doesn’t that make him sound charmingly self-effacing? He sounds like the perfect foil to David Cameron.