Garry Sobers made a significant mark on cricket history, not least as the man who first achieved the perfect six - six sixes in an over.

The 1968 season was nearing its conclusion when Nottinghamshire, captained by Sobers, travelled to St Helen's in Swansea to meet Glamorgan. The home side were a distant second to Yorkshire in the Championship, with Nottinghamshire back in fifth. But a victory for the visitors would lift them into fourth and win Sobers a bet and a case of champagne.

Nottinghamshire won the toss and batted, making reasonable progress on the Saturday. At 308 for 5, Sobers decided that quick runs were needed for a declaration that would allow his bowlers a crack at the Glamorgan top order before the close.

Runs came quickly, and then Sobers really opened up. The victim was Malcolm Nash, a 23-year-old left-arm seamer who was experimenting with spin bowling.

"The captain asked me if I fancied having a go at bowling some slow-left armers," Nash told The Guardian recently. "Sobers came along and quickly ended my slow-bowling career. It was a pretty short experiment."

Tony Lewis, Glamorgan's captain, remembers things slightly differently. "Nash believed if he tried the [Derek] Underwood style, he could top the averages," he said. Nash already had four of the five wickets to fall with his seamers.

Sobers decided on all-out attack. "I wasn't bothered if I was out or not," he said, "all I was interested in was quick runs and a declaration." Everything was in his favour. Nash wasn't turning the ball much and the pitch was over on the Gorse Lane side, presenting a short leg boundary for the left-handed Sobers.

The first two balls of the over were brutally heaved over midwicket, the first out of the ground, the second into the well-populated stands.

Nash responded by pushing the third delivery wider to the off but Sobers simply hit it straighter over long-on, hammering the ball with such force that he lifted his right leg off the ground as he connected, despite almost no foot movement.

Lewis ambled over and spoke to Nash. "If you want to go back to the usual stuff and whack it in the blockhole, that's fine with me," he told him. "I can handle it," Nash replied. "Leave him to me."

The fourth delivery was straighter; Sobers pulled the ball over backward square leg and it cannoned off the concrete terracing and back towards the square-leg umpire. "It was only then that I contemplated going for the six sixes," Sobers said. The crowd, however, were ahead of him and had started chanting "Six, six, six."

The fifth delivery was again straight and pitched up, and once more Sobers smashed it back over Nash from the crease. This time, though, he didn't middle it and Roger Davis, back-pedalling at long-off, jumped backwards as he took the catch and landed over the rope. There then followed a minute or so of confusion. Sobers started heading back to the pavilion, believing he had been caught. Davis shrugged and indicated he was unsure if the catch had been clean. Tony Cordle, the fielder nearest to Davis said it was a six. The crowd were yelling for Sobers to continue. The two umpires slowly converged, consulted, and then Eddie Phillipson turned and, to roars of approval, signalled another six.

Lewis then sent all his fielders to the boundary, the majority of them on the leg side. Sobers guessed that Nash would bowl a quicker one, and he guessed right. Not only was it quicker, it was also short, and Sobers, who by his own admission was seeing it like a football, rocked back and cracked the ball high over midwicket, out of the ground and trundling away down King Edward Road. It was returned the next day by a schoolboy and now sits in the Trent Bridge museum.

In those days it was not uncommon for regional BBC stations to cover local matches and BBC Wales was at Swansea. Wilf Wooller, the patriarch of Glamorgan cricket and the man who had led them to their first Championship in 1948, was on air. At the start of the over his producer told him to hand back to the studio. Wooller, who did not suffer fools gladly, refused. "He was so emotional that he got completely lost during the over," Lewis said. "It took days of editing to fix it for posterity."

In the Glamorgan dressing room Nash told team-mates not to worry and that he would "make a fortune out of it ... they'll make a movie". "What will they call it," one colleague replied. "Gone With The Wind?"

Sobers immediately declared and left the field to a rapturous reception. In the Glamorgan dressing room Nash told team-mates not to worry and that he would "make a fortune out of it ... they'll make a movie". "What will they call it," one colleague replied. "Gone With The Wind?"

"I could have bowled wide to try to stop him from scoring," Nash said later, "but that wasn't what I was all about. A couple of those shots would have got him out on any normal-sized ground. Are you going to sit around crying all day, or get on with what you do?

"On reflection, it wasn't that bad an over. I bowled one really bad ball, the last."

One bad ball or not, he will, harshly, be recalled for that one over and not for his 991 first-class wickets. "People will remember what they chose to remember," Nash shrugged. "'I don't reflect on it ever as a bad thing. That moment is, of course, all to do with Garry Sobers, and not much to do with me."

There are no hard feelings between the two players. "Since our retirements we've played a lot of golf together," Nash said. "We probably meet up about annually. We get on very well."

On August 29, 1977, Frank Hayes took 34 off an over. The bowler was again Nash and the ground was again St Helen's. Hayes' second strike went for four amid the flurry of sixes. "I never worry about the amount of stick I get," said Nash, "but the strange thing is it's happened to me at different ends of the same ground."

At the time the most runs off an over of six balls was 32 by Clive Inman for Leicestershire against Nottinghamshire at Trent Bridge in 1965, and also by Cyril Smart for Glamorgan against Hampshire at Cardiff in 1932. Nottinghamshire's Ted Alletson had hit 34 off one over during his amazing onslaught against Sussex at Hove in 1911 but that contained two no-balls.