Racing starts in competitive swimming, before the no-false-start rule, was known as a three start rule. The three start rule allowed for the potential of an anticipated start without disqualification. I relished in this.
In the three start rule, if a swimmer went early, the Starter would stop the race by a false start rope dropping across the pool and the swimmers were recalled. Sometimes the decision that the start was not fair was bit late so there was a bit of a palaver as swimmers swam under the false-start rope. An entertainment of questionable humour as a Referee and Judges ran down poolside blowing their whistle repeatedly whilst good samaritan swimmers tried to use the backstroke flags to stop them.
The ‘no false start’ rule that is in place today, is exactly that; no leaving early or automatically you are disqualified. You would even be disqualified at the end of the race for leaving early. Always an unhappy event in a 1500fr or a 400im

In the three-start rule; the first start was often prone to one swimmer diving purposefully early. More often than not this was to annoy the other competitors who were eager just to start racing. Or also likely; a swimmer just wanted to get wet before racing to wake themselves up and purposefully annoying their competitors. Another false start was caused by swimmers trying to anticipate the signal. This was an art.
If the first start was recalled, the second start normally was the start that started the race, not very often did the race go to the third start.
However if the race was recalled due to a ‘jumper’ on the second start, then the third start rule would be employed: any person in any lane moving early was disqualified. Basically this third start scenario is the rule in place today.

The lost skill that few swimmers attained was the perfect timing of an anticipated start. A fine line between anticipation and a false start was only a fraction of a second. A fast reaction is around .6s so I think a perfectly anticipated start would have been .3s. Sadly it is a lost skill because the risk of disqualification.
Likely it wasn’t a sad event when the rule change happened for Referees or Starters since every false start increased the time spent running the competition.
However without any empathy for officiating, a perfectly anticipated start, had to be so perfect that a Starter would let it go.

I loved nailing a perfectly anticipated start. I guess it might be a grey area like diving in football (soccer), no pun intended btw. But like a football dive it would win the event. It was part of a skilled swimmers’ repertoire of skills because an anticipated dive would net a swimmer at least a half a body length or more.
In a perfect ‘jumping the gun’ scenario, it was obvious that the swimmer started slightly before the others, but importantly, not before the signal noise for the Starter to recall the race.
Every now and then, in the perfectly anticipated start, a swimmer gained about three tenths of a second. Add into the mix; a huge dolphin kick and a smooth breakout, then a swimmer could pop up close to a whole body length ahead. Pure joy and a podium finish. Or a false-start rope around your neck.