The wonder of it is that it has taken so long. Sport has for decades been the ideal target for terrorism, both in terms of its accessibility and in the trenchant messages such action would have for the world. But until yesterday, sport has, with one great exception, been granted a strange immunity.

With the attack on the bus ferrying the Sri Lankan cricketers to a Test match, it is as if the terrorist forces of the world have suddenly become aware of what was under their noses all along. Sport is the world’s great soft target. And you could hardly find anything on Earth with such a high profile, already surrounded by media and watched by the millions and the billions.

The one occasion that big-time sport has been used by fully baked, properly trained and seriously motivated terrorists was in 1972, when the Black September movement invaded the Olympic Village in Munich. Eleven athletes and coaches were killed, plus one policeman and five of the eight terrorists.

But this action did not start a fashion. In this country the IRA announced that it had planted a bomb at the Grand National in 1997. This turned out to be a hoax, but it was an effective one — massive disruption combined with the cocking of a snook at British sensibilities and the ruling classes, which are supposed to love racing.

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The counter-myth of British Blitz spirit and the stable lad who stayed behind to look after the horses only emphasised the power that sporting events hold over the world’s imagination.

But mostly, sport has only been touched on the fringes by terrorism. Sport has not often been threatened, still less attacked.

It is true that events and tours have frequently been cancelled out of fear, much to the gratification of terrorists, no doubt. The Australian cricket team have become notorious for pulling out of tours any time that anyone lights a match within 500 miles of a cricket ground. American golfers pulled out of the Ryder Cup fixture in Britain in 2001 after 9/11, well aware that Britain is dangerously close to the Middle East.

But until now, sport has led a largely charmed life. It is hard to work out why. Sport, with its huge crowds and big spaces, is essentially insecure. Sport is already a stage and the world is watching. All a terrorist has to do is alter the script and all the publicity in the world is his to command.

I have been through a million metal detectors; my laptop has been X-rayed so often that it glows; my bag has been fumbled with and my crotch groped repeatedly by the uniformed and the charmless; and I know that all this performance is just for the look of the thing and that a professional could get through with anything he liked.

You just can’t make a crowd of thousands secure. Time after time, as I have gone through security, I have wondered what, with know-how and planning and training, I couldn’t bring into Wembley or to Centre Court, Lord’s or Twickenham, the Olympic Games or the World Cup Final.

Sport is also intimately caught up with nationalism. To attack a nation’s sport is to attack something that matters profoundly, in all sorts of complicated ways, to the people of that nation. Just think of that bomb on Centre Court and you will see what I mean.

But there is something still closer to the heart of a properly vengeful terrorist waging war against the world gone wrong. That is frivolity. Sport is an essentially trivial activity. To the puritan mindset, sport is a living statement of the world’s failure to take your issue of choice with the right kind of seriousness. If you attack the frivolity of sport, you are trumpeting in the loudest fashion possible the absolute and irrefragable seriousness of your own cause.

There is yet one more reason to make sport an attractive target. That is because sport is about joy. Sport is uniquely capable of uniting great numbers of people in wonder and delight. What terrorist in the world would not wish to turn that joy to ashes?