Until Andrew Flintoff and Simon Jones last summer, old cricket balls were mostly useful in Pakistani hands. Explanations for reverse swing came within quotation marks, accompanied by winks and nods - "working hard on the ball" or "rough outfields help" mostly meant "show me a finger nail/bottle top and I'll show you a collapse". Last summer reverse swing became a science. Fast arm actions helped as well as strong shoulders and a bit of whip to your action. Vindicated Pakistanis blustered. They might also have pondered the role of the tape ball - a tennis ball covered with electrical tape.

Ostensibly, it appears to have had a pivotal role. Non first-class cricket in Pakistan has been played with a tape ball in every galli (lane) and rural field for 20 years. Parallel to this period has been an assembly line of fast bowlers, able to extract reverse swing almost on demand.

Slightly heavier than a tennis ball, a tape ball behaves more like a cricket ball, retaining greater pace off the surface with sharper bounce. Lighter than a cricket ball, the weight, according to Rashid Khan, a former Test bowler, coach and tape-ball don, is crucial in developing pace.

"With a lighter ball your arm moves round quicker for more speed. Successful tape bowlers really slip off the surface . . . eventually when you play with a hard ball you have a quick arm and greater speed."

Aqib Javed - Wasim Akram and Waqar Younis's back-up in the 1990s - suggests bowling lighter balls strengthens muscles, "producing bowlers like Mohammad Sami - not big, but with a quick arm and so very skiddy off the pitch".

Rahul Bhattacharya noted in his book, Pundits from Pakistan, that a tape ball is bowling emancipation. Leave a tactical slit or place a double-layered seam and you have swing. Play enough and you discover that tattered tape on one side (creating contrasting surfaces and weight imbalance as with a cricket ball) and the right length buys sharp swing - reverse swing.

Sami, on Karachi's congested streets, and Rana Naved-ul-Hasan, in the more tranquil Sheikhupura near Lahore, both learnt reverse with tape balls. Umar Gul did not play with a cricket ball until he was 16 and says tape balls increased his pace and helped him develop greater control.

Khan, though, points to the gaggle of bhatta bowlers (chuckers) who have emerged as a downside. And given the scarcity of quality Pakistani batsmen since the late 1980s, nobody is certain how it affects batting. He remembers bowling to Saeed Anwar "with a tape ball for hours on end" in the late 1980s. "He practised pulls, hooks, cuts and all from 18 yards, so his reflexes sharpened up." As one of the game's best openers for a while, reliant on hands and eyes more than feet, Anwar provides meat to a thin argument.

Some argue it sharpens technique - with little evidence - although it is popularly recounted that before the tour to West Indies in 1987-88, Imran Khan, in a bid to prepare his batsmen, made them practise against a tape ball from 18 yards. The story is not entirely true: Imran revealed they practised with an ancestor of the tape ball - the wet tennis ball.

Nazimabad, a middle-class area in Karachi's north that is home to a rich, cut-throat, high-quality cricket culture, is widely accepted as the focal point of the tape ball. So when and how did it begin?

The experience of the left-arm spinner Nadeem Moosa, a first-class cricketer in the mid-1980s, offers a credible starting point. He is more celebrated as a tape-ball player. Having played with a bald tennis ball for years, Moosa developed the "finger" ball. Delivered from a subtle bastardisation of Jack Iverson's unique grip, the tennis ball additionally squeezed to offer sharper top spin and break, Moosa was, in his own modest words, "unplayable" for years. Cricket then did what it does, taking from bowlers and giving to batsmen. Moosa's contemporaries decided that covering the ball with tape would make it harder to squeeze, preventing the finger ball. So the tape ball was born in 1984, since when its use has burgeoned. Rashid Latif, the former Pakistan wicketkeeper and captain, claims "70% of all cricket is now tape ball".

The slow death of school cricket helped. While Mushtaq Mohammad, Javed Miandad and Imran learnt as much in school as on streets, much of today's generation have no choice but to play tape ball in their mohallas (localities). Lack of space and grounds, particularly in Karachi, has further propelled its ubiquity.

No tape ball league exists but you are likely to find a game anywhere. During Ramadan it becomes serious. Big-money tournaments attract legends and internationals such as Latif and Shahid Afridi, and games go on until dawn. Somewhere here, almost guaranteed, lurks Pakistan's next fast bowler.