ANDY Murray is getting on a bit.

That might sound rich coming from a 55-year-old, but in tennis terms it's true.

He's 28 now, into his second decade as a Wimbledon competitor, and in the latter half of his life as a serious contender for major honours. As his mother Judy has said on several occasions, the sport needs to exploit his example while he is around. And in fact, although she would not say so herself, tennis needs to make the most of the indefatigable Judy too, because she has arguably done more than any other individual in recent years to promote it - from her coaching of young children to her captaincy of Britain's Fed Cup team.

It is hard to know the precise number of people playing tennis in the UK, because a lot of them do so away from clubs, on public courts where there is no-one to count the numbers. As far as Scotland alone is concerned, one estimate is that the number has roughly doubled in the last decade - in other words, since Murray made his debut at the Championships.

Inspiring people to take an interest in the sport is the first thing that needs to be done, and the success of Murray has done that all right. Once you have attracted them to play tennis, you then have to ensure you have the facilities to enable them to play regularly. And, with the young in particular, you also need to have enough coaches around to help them improve and hopefully take a long-term interest in tennis.

A detailed assessment of how well Tennis Scotland in particular has done in those respects is beyond the scope of this column, although Jamie Murray, for one, is convinced they could and should have done a lot more, and said so unequivocally at the start of this year. But the simple reality, no matter how pessimistic it may sound, is that the governing body could pump in tens of millions of pounds more into new facilities and coaches, and yet still suffer a steady reversal of fortunes once Andy Murray retires.

Let's be honest: with the best will in the world, and even if every second school student in Scotland takes up tennis, we will not unearth another Andy Murray any time soon. We will get more competitors playing more consistently down the echelons a bit - fighting to be among the best in Britain and in with a chance of winning places in the Davis or Fed Cup teams - but it would be a major accident of fate, genetics and history if anyone else emerged anytime soon who came close to winning a major.

It will be interesting to see - and tennis should watch this one carefully - how cycling fares over the next few years. At present, it still seems to be enjoying a bit of a boom, thanks to Sir Chris Hoy, Sir Bradley Wiggins, Chris Froome and their colleagues. But, less than two years after the Scot's retirement from competition, we are probably close to the point when kids start asking their parents "Who was Chris Hoy?"

That is no disrespect to our greatest Olympian. Rather, it is a simple recognition of the fact that most people take inspiration from things that are happening around them, rather than from those, no matter how spectacular, that took place a few years ago.

Athletics in Scotland offers a similar example. When Allan Wells was in his pomp, sprinting must have enjoyed a boom in interest, but it did not lead to a succession of Scottish Olympians in the 100 and 200 metres.

And remember when, after London 2012, athletics clubs across the UK enjoyed a massive increase in numbers? Many were unprepared, with the result that lots of potential successors to Jessica Ennis-Hill, Greg Rutherford and Mo Farah were lost to the sport.

That is just one respect in which football has a massive advantage over every other sport. Not only does it receive far more publicity every day, it is something that you can pick up with minimal equipment. With just a ball you can practise a lot of football skills, with a ball and a wall even more. A ball and a wall and a second person to compete against and you're on your way to being ready to take part in matches.

And that simplicity is why football will continue to expand. Look at the two most populous countries in the world, with over a billion people each, India and China. Vast though they are in terms of population, both are nowhere in footballing terms.

This will change - in fact, it's already doing so, as China showed in getting to the quarter-finals of the current Women's World Cup.

It is counter-productive for other sports to complain about football's domination, but they are likely, in the decades to come, to have an increasingly difficult job competing against it. Which makes it all the more vital that, when someone as extraordinarily gifted as Andy Murray turns up in a sport, those in charge do everything to make the most of him while they can.