Pick up any dictionary and check the definition of honesty. There will be references to integrity, loyalty, candour, right-mindedness, authenticity. All of these describe the Andy Murray I have come to know and, without wishing to confer sainthood on the poor man, the best tennis player these islands have had and the freshly crowned No1 in the world would still seem to be incapable of telling a lie.

That is at the core of his genius. There is nothing fake about what Murray does on court or, as far as evidence suggests, off it. The sweary, chuntering, foot-dragging sufferer who prevails to conquer all real and imagined demons will not change just because he now looks down from the mountain instead of up.

It is one of his towering achievements that he is essentially no different to the Murray barely any of us knew when we first became aware of his talent a decade and more ago. More than likely, he has changed little in character or demeanour since his mother, Judy, gave him and his brother tennis rackets in Dunblane when they were no higher than the net at the local club.

One of the most touching images to reach public view after his triumph in Paris at the weekend - to seal not only the Masters title there (his eighth of the year) but take the crown of his longtime rival Novak Djokovic - was that of his mother sitting on his knee, holding a glass of champagne as they flew home on a private jet. Their smiles were frozen in the photo but more than likely did not disappear after the click of the button.

She was there for him at the beginning, during countless swoops and dives, and here at the moment of what might prove to be the defining achievement of his career. Some have cavilled at her presence, weirdly. It bothers neither her nor her sons.

So, how has he done it? Perhaps the key to his continued success in the toughest era of his sport has been his almost maddening attention to detail. He shares that obsession with Djokovic, whom he has known since they were 11 and against whom he has always judged himself. No minor detail is too small to master, for either of them.

As the Scottish journalist Hugh MacDonald says in his concise and exquisite book, Murrayball: How He Gatecrashed the Golden Era, Murray rose from the most unpromising tennis environment imaginable in a small Scottish town to the heights of the game by “taking the small steps, by intuitively and then efficiently employing the theory of the aggregation of marginal gains”.

Murray has never lacked for friends in the game - as the vanquished John Isner testified after losing in three sets to him in the final on Sunday. "He's the guy that everyone is looking up to right now," the American said after his eighth straight loss to him. One of the first messages of congratulations Murray received from outside his immediate family on the evening he reached the pinnacle of his sport came from Tim Henman, who was similarly misunderstood in the years that he carried the weight of British expectations at Wimbledon and on less amenable surfaces to his particular talent.

Henman has been a generous and supportive ally of Murray’s since their careers briefly overlapped and said in one early biography: “I remember when word first reached me about ‘this kid with an unbelievable feel for the game - always seems to play the right shot at the right time - but he’s a bit temperamental on court.’ That should remind us of someone. All those characteristics are still there.”

Sue Mott ghostwrote that book before Murray won the Olympic gold medal in 2012 and three subsequent grand slam titles. However, the point Henman makes is valid still. Murray had not changed at that point in his career and he remains as stubborn, committed and intuitive several years on.

I first saw him play in New York in 2004, the year he beat the cerebral and quirky Ukrainian Sergiy Stakhovsky 6-4, 6-2 to win the boys’ title at the US Open. For all that he had what Henman identified as a natural instinct for the game, there was little to suggest that Murray would prove to be any better than many other prodigies who had washed up on the shores of our collective imagination.

He was frail, for a start. That year, he had spent six months out with a knee injury. After he joined the Tour the following year, he was out for three months with the first signs of the back problems that would plague him until he finally went under the knife eight years later.

Now he is at the peak of his powers. There will be twinges and grimaces, certainly - but the superstructure he has constructed is as strong as it could be. So is his mind. Murray is 29. Those around him are starting to falter, even Djokovic. It could be that the next few years we will see a more dramatic flowering of the most remarkable athlete it has been my pleasure to know.

Guardian Service