On other days there might be bananas and prunes, vanilla and apricots while he speaks lovingly of woody flavours, of pear drops and fruit. But Mr Robertson is not tasting wines to discern their flavours. He isn't tasting anything, because the drink he dissects by its myriad aromas is the Macallan single malt whisky, and he does it all with his nose.
Mr Robertson is the Macallan's chief noser at its Speyside distillery in the Highland village of Craigellachie. It is his job to ensure that the inconsistencies inherent in taking water, barley and yeast, in distilling them and laying them down for years in oaken sherry casks are wiped out. He uses the contents of his trusty carrier bag to identity smells and to change, mix and marry the contents of the barrels to make the perfect Macallan.
But last week Mr Robertson was at the centre of an unseemly row. He rose to his position in August at the age of only 28 following a hostile takeover of the Macallan distillery in a joint pounds 180m bid by Highland Distilleries and the Japanese liquor company Suntory.
His predecessor, Frank Newlands, 55, was squeezed out in the boardroom coup along with three other nosers who last week told the Wall Street Journal that they feared for the future flavour of the Macallan.
Under the headline, "Nosers Out of Joint", the other nosers expressed fears that the Macallan might suffer in Highland Distilleries' drive to push up exports - already at 130,000 cases a year - and because of Mr Robertson's relative inexperience.
He had been, said the newspaper, "steeped in the Macallan tradition for under three years", while Mr Newlands had been steeped in it for 22.
One former executive told The Independent that four members of a six- man nosing panel had been made redundant. "You can't tell me that won't have some effect," he said.
But Mr Robertson and Peter Fairlie, the new sales director, disagree. "Only one of the main panel of four was made redundant - Frank Newlands," said Mr Fairlie. "The others were good nosers but they were regarded as occasional nosers, not what we would consider the hardcore of four regulars who we still use.
"It is unfair to criticise David because of his age. He has an exceptional talent and is very well respected in the industry.''
Mr Robertson, a man liked even by those he replaced, has been embarrassed by the fuss.
"My father was assistant manager at the Brackla Distillery when I was born and I grew up on distilleries as my father moved around," he said. By the time he went to Edinburgh to study for a degree in brewing and distillery his talent for nosing had already been spotted.
"I don't get hurt by what has been said, but I do get a wee bit embarrassed about the impression that I'm just out of my nappies. Who's to say that a younger nose isn't better, fresher, more receptive?
"What has happened has been unfortunate, but all those involved have always had the same interests at heart - to make the finest possible Macallan - and we all know that we're only here for a while. Each one of us will always have to hand on the torch to the next generation.''Reuse content