Who coined the term reverse swing? I think it was Imran, but it would be good to have it verified.I'm afraid that you will have to go back quite a bit further than the early 1990's - the tour which had Alan Lamb up in arms about 'one or two things'.Why does a ball reverse swing?
I have studied film of many fast bowlers over the last 30 years and (unless I am mistaken) the 'first' exponent I ever saw of reverse swing was Sarfraz Nawaz with his 'in-ducker'.
As far as 'who first used the term "reverse swing"', that's more difficult. It's a term which has crept into cricket in the last 10 years and everyone uses it. I have conducted searches through my cricket books and the internet and cannot find a single reference to the term before about 11 years ago.
There was a scientific study of the mechanics of cricket ball flight published in 'New Scientist' in 1980, and this deals with 'smooth v rough' sides of the ball, but the modern phenomenon is 'wet v dry'.
I would guess that the first time anyone discovered the phenomenon would have been a total accident. When I was at Derbyshire's indoor nets about 30 years ago, it was like an old 'nissan hut' - a prefabricated structure with a metal roof. In winter, it used to get pretty steamy in there with plenty of condensation.
I could envisage a scenario where a ball had been 'left behind' in there, and a damp or wet area of condensation had formed overnight (say under an old polythene sheet). The next day, someone comes in for a 'net' and finds the ball. One side's dry, one side's heavy with water. The bowler holds the ball as if to swing the ball conventionally, delivers it and it goes 'the other way'.
Now, it wouldn't surprise me if someone (e.g. Sarfraz down at Northants) discovered this phenomenon quite by accident. It would then become a closely-guarded secret. Unfortiunately for bowlers, the whole issue was blown wide open in the early 1990's with accusations, counter-accusations, recriminations and the like.
The 'mystery ball' was no more, and scientific studies eventually confirmed the reason for reverse. Not (necessarily) ball-tampering, but the 'loading up' of one side of the ball with perspiration.
Didn't really answer your question Roy, but I had fun researching it as much as I could.
Did it answer Mr Perko's? Not totally, but there are many studies which have been performed, and I don't feel right just reproducing their work here. Just use a search engine, plug in 'reverse swing' and away you go. If there are bits you don't understand regarding the aerodynamics and so on, feel free to ask us again.