Paul Gray, you must all know by now, was the HMRC chairman who resigned yesterday (Tuesday) over the loss of the data. It was an astonishing failure, but I can't help feeling sorry for Gray.

Here's why. Though there were rules in place, guidelines established, absolute prohibitions set, some IT lunatic took it upon himself to ignore all common sense and burn the data to a couple of discs and pop them in the post for the National Audit Office, only for the discs to go missing en route.

If you are a leader you can't quite legislate for the office maniac who ignores all the rules and does something that reaches the absolute pinnacle of stupidity.

Paul Gray is not alone in this. Think of Barings Bank, the classic business example, brought crashing down by Nick Leeson sitting in Singapore acting in a manner that not only defied his pay grade, but all accepted notions of rational behaviour.

Go back in history (this one's a stretch, so bear with me) and think of the Spartans at Thermopylae undone by a disgruntled shepherd who led the Persians through a mountain pass.

I can't help thinking therefore that leaders are at the mercy of juniors who become loons overnight, insignificant individuals who demand not a second thought but somehow manage through fate, ill fortune, spite or sheer ignorance to tip the balance in favour of catastrophe.

Paul Gray was well liked by the profession, and HMRC insiders, and looked as if he was on the way to sorting out many of the problems that have beset the taxman of late. He will be sorely missed and but for one lone madman (OK, there should have been a system alarm triggered by any efforts to download such a mass of data) he might still be in place.

As one former Revenue chairman said to me yesterday: 'There, but for the grace of God...'