Wasim Akram and Waqar Younis achieved two things in the English summer of 1992. They perfected the first genuine fast bowling innovation since overarm bowling was legalised in 1864. They also provoked repeated controversy and unproven charges alleging that their success was entirely dependent upon illegal tampering with the ball.

True or false? Fair or foul? Trick or treat? The facts first. Bowlers throughout history have bowled as fast as the Pakistani Pair, and other bowlers have achieved a similar amount of late swing, but never in living memory have two bowlers achieved so much late movement through the air at such a pace … and usually with the old ball.

Their series statistics are impressive enough: nine games between them, in which they bowled 334.5 overs for 1,019 runs and 43 of the 71 wickets taken. They took a wicket every 46.72 balls. Furthermore, of the 43, 26 were bowled or lbw, and 14 more caught in the arc from wicket-keeper to gully. The fingers started to point because a second new ball was invariably refused by the Pakistan captain, Javed Miandad, and because there were five astonishing collapses by England when, from positions of relative prosperity, their batsmen were swept away by Wasim and Waqar with a ball well over fifty overs old.

It started in the Lord's Test, when England went from 197 for three to 255 all out and 108 for two to 175. At Headingley, the genies rubbed their old lamps to even greater effect, with England collapsing from 270 for one to 320 all out. At The Oval, they went from 182 for three to 207 all out and, in the second innings, from 153 for five to 174 all out. That is an aggregate of 221 runs for the loss of 36 wickets, with the two fast bowlers taking 24 of those wickets. The carnage happened, not at the start of an innings when, traditionally, the brand new ball is a fast bowler's most lethal weapon but three or four hours later, when the ball was older, softer, and with a less prominent seam.

All the men who have revolutionised bowling in the past have been spinners: Bosanquet with the googly, Grimmett and Benaud with the flipper, and Iverson, Ramadhin and Gleeson, who all baffled batsmen with a freakish grip. Of course there have been great swing and swerve bowlers throughout the 20th century – George Hirst, Fred Root and Bob Massie for example. But they were not genuine fast bowlers. Nor did they become more penetrative as the ball got older. It is this crucial difference which sets Wasim and Waqar apart from all other bowlers, because their methods go against all previously established principles, most of which have a sound scientific basis.

Traditionally, swing bowlers have obtained their movement through the air by maintaining the seam in a near-upright position to act as a rudder, with one polished side of the ball providing less resistance than the rougher side, with the result that swing is induced in the opposite direction. But bowlers have often found practice harder than theory, especially at the optimum speed for late movement in the ball's flight path. And there has never been a satisfactory logical explanation why one ball swings more than another, or for the relevance of humidity.

Wind tunnel experiments have established the vital importance of the seam. If the ball had no seam, it could swerve but not swing. As dimples on a golf ball make it fly further, so the seam of the cricket ball energises the air, reducing the resistance on one side and making swing bowling possible. Experiments at the University of Sydney have established that a bigger seam makes the ball swing more, and that new balls swing more than old. A team of scientists from Imperial College, London decided that optimum swing was achieved at around 60 mph with the seam at 20 degrees from the line of flight. Nobody argued with the boffins, because the theories fitted the facts and vice versa, but Wasim and Waqar have achieved violent and late swing at 80 mph despite ignoring three basic principles.

• They do not swing the ball while it is new, yet obtain extravagant movement after three or four hours of use.
• They do not rely on one side being highly polished.
• Particularly in the case of Waqar, the ball is not held loosely by the first two fingers and a thumb, but often wedged firmly into the palm of the hand, baseball pitchers' fashion.

What did happen is that the Pakistanis avoided the traditional method of keeping one side highly polished. Instead, by keeping one side smooth and allowing the other to roughen with use, they converted the normal evenly-weighted cricket ball into one with bias: i.e. the smooth side would be wet with sweat and spit and would become heavier than the dry, rough side. The net effect makes the ball behave like a bowl which is officially weighted to produce bias.

The wetting of a ball is legal, providing only natural properties are used, and so is a natural roughening. But that alone will not turn an ordinary bowler into a devastating one. Remember that Wasim and Waqar have played in county cricket, but no other Lancashire or Surrey bowler has suddenly developed the ability to swing the old ball so much – although Surrey have been reported several times for illegal interference with the ball. Even more significantly, the Pakistan support bowler Aqib Javed has not benefited anything like as much from any so-called doctoring. It is one thing to prime a hand grenade; the trick is knowing how and when to pull the pin.

To get the right effect, the ball needs to be held correctly and, in order to generate late swing, propelled fast and at near-yorker length. This calls for a degree of ability and control which is beyond most bowlers, who are neither quick enough nor accurate enough to bowl yorkers at more than 80 mph. The length is crucial. Neither Pakistani fast bowler swings good-length deliveries simply because, it their pace, the bias of the weighted ball cannot come into play until the ball slows down. It is not in the air long enough when it travels the good length distance of about 45 feet. It is only when the ball travels the extra distance into yorker territory that the subsequent slight decrease in pace allows the bias to work. The principle is the same as in golf, where a long putt breaks more as the ball loses speed towards the hole, and in bowls, where the bias of the bowl is more pronounced towards the end of its journey.

The key to all this is the position of arm and hand. Neither Wasim nor Waqar has a high arm, and the violent in-swing of Waqar is complicated by the dropped right arm and his point of delivery, which is close to the stumps. He thus has the ability to start his line outside the right-hander's off stump, and it is against that angle that the late and pronounced swing becomes virtually unplayable. Most revolutionary of all is Waqar's grip, which uses most of the hand and fingers. According to the Imperial College theory, if the seam is canted 20 degrees to leg side and the smooth polished half faces the off side, the result is an in-swinger. Waqar reverses this by holding the ball so that the smooth, damper half faces leg side and, because it is heavier, drags the ball that way. Hence the phrase  reverse swing. The skill still lies in the ability to bowl fast at yorker length. Imran Khan claims he could reverse-swing the ball in England from mid-July onwards when most of the county squares became hard and worn. He quotes the Lord's Test in August 1982 as an example of his ability to move the ball when the England bowlers, using conventional methods, achieved no movement in the air at all.

So fair or foul? It is perfectly legal to make one side of the ball heavier by sweat and spit (as opposed to Vaseline or sun cream), therefore reverse swing itself is legal. It only becomes illegal if the bowlers are hastening the process by making the rough side lighter and gouging bits out. That is the element that brought the cries of Cheat. There is, in my view, a strong case for widening Law 42.5 to allow a reversion to the practice permitted before 1980, of rubbing the ball on the ground to let bowlers, usually spinners, get a better grip. If sweat and spit are permissible to shine or dampen one side of a ball, why should the other side not be rubbed in the ground? The balance of cricket has shifted so far in favour of the batsmen that treatment of the ball should be permitted, as long as umpires can control it and there is no alteration of the condition of the ball, i.e. no tearing away at the surface until strips of leather are removed.

Only bowlers with the ability to bowl fast and with the control to bowl yorkers, such as Wasim and Waqar, would benefit – as would the game of cricket. Bouncers were hardly used in 1992 by two bowlers who are to be congratulated for producing some of the most spectacular bowling that spectators in England have ever seen. Any genuine innovation in sport is fascinating to watch. Wasim Akram and Waqar Younis won the series for Pakistan on superior ability. A minor change in Law 42.5 will ensure that neither they, nor future successful imitators, need have their feats clouded by controversy.

 Jack Bannister is cricket correspondent of the Birmingham Post and a BBC commentator. He played for Warwickshire between 1950 and 1968 and took 1,198 first-class wickets.

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