THE phrase ‘quit while you’re ahead’ is in common use, but can rarely be applied in its truest sense, especially in the field of sport.

Double congratulations are due then, to Nico Rosberg, the newly crowned world Formula One motor racing champion, firstly for a fine season behind the wheel, and secondly for managing to keep his impending retirement a secret.

In a world where digitally-powered rumours and leaks abound, many of which turn out to be true or have at least a grain of truth about them, Rosberg’s announcement yesterday of his retirement came as a genuine surprise.

But he has his reasons, and they are good ones, not least that he wants to do ‘family stuff’ for a while.

And at 31, he has, in his own words, “climbed my mountain. I am on the peak, so this feels right.”

It is a summit that has taken more than a decade to reach, having begun in F1 in the 2006 season which, it is fair to say, did not go too well.

But he has stuck at it. Gradually, he has driven himself to the top of a sport that he was pretty much destined to participate in, overcoming many physical and mental hurdles on the way.

Listening to him explaining his retirement yesterday, it was not difficult to detect an immense emotional and physical weariness behind the euphoria, most of which has in all probability accumulated during the past three seasons of epic battle with teammate Lewis Hamilton.

To be blunt, Rosberg really should have won the title in at least one of the past two seasons but a combination of poor luck, poor judgement and Hamilton’s indomitable will to win ground him down.

This year, he capitalised on Hamilton’s difficulties, to establish a points lead which he was able to defend despite his teammate’s late season resurgence.

Last week’s Abu Dhabi Grand Prix was his final test, and he remained calm despite Hamilton’s slowing down of the race, bringing other drivers closer to Rosberg, to try to put more places between them in an effort to retain his title.

It is fair to say that the Rosberg of 2014 and 2015 might have cracked under that pressure. Not this time however. he appeared unflappable, and his title was well deserved.

Fast backward 34 years, to 1982, perhaps the last time - before 2014 - that I was interested in F1 for a whole season, as opposed to the odd race.

That year, Nico’s dad Keke emerged triumphant against the odds, winning the title in a car with a V8 engine, thus stalling the subsequent dominance of the turbo era.

If that makes me sound like a petrolhead, the impression is a false one. I barely understood the difference, but knew that Keke Rosberg was racing at a disadvantage - and in sport, I love nothing better than an underdog.

True, the turbos were having teething problems, but they were meant to be superior. Rosberg meanwhile, took advantage through a combination of greater engine reliability and canny, gutsy driving.

Remarkably, Rosberg Snr won just one grand Prix that season.

But the points system back then rewarded consistency in the lower placings, and nine top five finishes, including three second places, saw him home as rivals’ race retirements clocked up.

That was a season which saw the awful, televised practice lap death of Canadian driver Gilles Villeneuve, and a terrible crash - again in practice - that ended the career of Frenchman Didier Pironi, who at the time was the championship leader.

It was a season memorable for all the right and wrong reasons, and Keke Rosberg’s ultimate triumph was to shine a little light on the darkness.

Having shown plenty of commitment and mental strength during his years behind the wheel, Rosberg Snr was quick to praise the same qualities in his son after he clinched the title last weekend.

Like father, like son, indeed.

And from this sports fan at least, the goodwill message is a little simpler: Thanks both, for making F1 interesting.