This column began as a pub bet. It being the Fink Tank, however, it was settled only after a week of computer modelling and some head-splitting discussions about trigonometry and “squared angles”. Don't worry, I will spare you the gory details.

Like all football fans, I have watched a large number of free kicks being shot at goal and I developed a theory. I thought that there came a point when closeness to the net became a disadvantage.

So you were, say, in a great spot if you were taking the kick from 20 yards, but if you were hitting it from 18 yards it would be harder to get the ball up and over the wall.

Dr Ian Graham disagreed. He feels that the nearer the goal you are, the better it is. There is, he said, no “sweet spot” a little farther outside the area. The bet was on. Together with Dr Henry Stott, Ian set about studying the free-kick shot on goal.

In How to Score, his invaluable book, Ken Bray suggests that to comprehend free kicks, you need an understanding of fluid dynamics (Chelsea should get Ashley Cole to take them, then). But I think we will all just about struggle by without it.

Bray's work suggests that there are two difficulties for the kicker that increase the farther out you go. The first is the need for accuracy. Bray estimates that to score with a side-spin kick from 20 yards, the ball has to hit an area only eight balls wide as it goes over the wall. At 25 yards, the area it has to hit is only six balls wide.

The second problem is the need to catch the goalkeeper out. The typical speed of a free-kick shot is 25 yards per second. That means the goalkeeper has one second to react at 25 yards, but only 0.72 seconds to react at 18 yards. However, there is one advantage to distance. Free-kick experts can put a spin of about ten rotations per second on a ball. The farther out you are, the more the ball spins before it arrives at the goal.

Fink Tank analysed 679 matches from the past three seasons and found that there were 1,009 free kicks shot at goal. Despite the crowd excitement that greets every kick, surprisingly few end as goals. Only 60 in total.

Why do so few go in? One reason is that 34 per cent of the shots are blocked by the wall. If a free kick is on target it has about a 24 per cent chance of going in - that is similar to the normal rate of conversion of shots on target into goals. What that means is that if you are able to shoot at goal in open play, it may be easier to score than it is from a free kick.

As the graphic shows, when more than 30 yards out, players are more inclined to pass than to shoot and beyond 36 yards they pretty much stop shooting at goal. That is common sense.

But a more odd result of our analysis is that the success rate of free kicks does not seem to vary with the tightness of the angle. There is, however, a simple explanation. The moment the angle becomes even mildly tight, players pass instead of shooting.

And the bet? I lost, Ian won. But only narrowly, Ian, and using a very small sample of goals. But OK, there is no sweet spot. You score more the closer you are. Good thing we never agreed to put money on it.