As a six-iron shot, it could hardly be rated alongside the magnificent effort of 210 yards which Seve Ballesteros hit to the 17th at St Andrews, his penultimate hole, en route to victory in the 1984 British Open. Nor could it be compared with the stunning bunker recovery over water to the 72nd at Glen Abbey, which delivered victory to Tiger Woods in the Canadian Open last September.

Still, it gained the distinction of provoking a reaction, albeit a mixed one, from no less a body than the Royal and Ancient.

In February 1971, a telegram was despatched from St Andrews with the message: "Warmest congratulations to all of you on your great achievement and safe return. Please refer to Rules of Golf section on etiquette, paragraph 6, quote - before leaving a bunker a player should carefully fill up all holes made by him therein - unquote." Three years later, the club which executed a shot, literally out of this world, was presented to the USGA Museum in New Jersey. And the donor was Alan Bartlett Shepard Jnr, pilot of Apollo 14.

"I really didn't develop an interest in golf at a young age," he said. "I played a little bit and knew the basics of the game, but I guess I never really got serious about it until I got into my forties." One of the advantages of being a US astronaut at the Johnson Space Centre in Houston during the 1960s, was the opportunity it afforded of meeting some of the great names of the game. For instance, Shepard received some very helpful tips from the 1956 US Masters winner, Jackie Burke, who founded the Champions Club at Houston with Jimmy Demaret.

"It wasn't a regimented type of thing," the astronaut told Rich Skyzinski of the US Golf Association in the course of an interview in 1996, two years before he died.

"I'd be out there practising and Jackie would come along and give me a hint from time to time. I guess that's where the seriousness of it all started."

Shepard, who was then a 15-handicapper, explained: "I think what he tried to tell me was that, as an engineer, I was too regimented; that I should relax and enjoy the game. I remember that, and sometimes when I get a little uptight about it I try to remember Jackie's words of just relaxing and trying to have fun."

After the near-disaster of Apollo 13, it clearly took tremendous courage for Shepard and his colleagues to go into the small nose-cone on top of a rocket and be propelled at 25,000 mph into space. He later reflected: "I think all the analyses showed that there was a chance probably one out of 20 flights would result in fatalities. And we were willing to take that risk, figuring that if it happened to somebody, it was going to happen to somebody else and not to us."

The enthusiasm for golf which Burke had instilled into him, led Shepard to come up with a fascinating idea for the Apollo 14 mission. And by way of making it workable, he visited Jack Harden, who was head professional at the River Oaks CC in Houston at the time, taking with him a retractable instrument which was used to collect dust and rock samples from the moon.

"I swore him to secrecy," said Shepard. "And then I asked him 'Is there any way we can make a six-iron fit the end of this strange-looking handle?' Sure enough, he cut off a six-iron, put a little fitting on it and we had it."

Aware that the lunar atmosphere would restrict his movement, he then set about doing some practise, so as not to embarrass either himself or NASA.

"I enlisted the secrecy of the fellow who handled the pressure suits," the astronaut explained .

He went on: "At night, after hours, I would go down to the suit room and put on the full suit, with the oxygen tanks and the radios and all that stuff, and practise swinging, which I couldn't do very well. But at least I got to the point where I was making some contact .... I wanted to be sure I didn't fall down, 'cause I planned to do it in front of the television camera."

Then came a consultation with Bob Gilruth, director of the manned space centre, who had the power to scupper the idea. And Gilruth's reaction was: "No, I don't believe we're going to do that. It's far too frivolous."

Undeterred, Shepard put his case a second time, armed with photographs he had taken from his sessions in the suit room. And he added: "How would it be if only a handful of people were to know? They would be people who have to know. How would it be if we go up on the lunar surface and we have any kind of problems - equipment failures, or we're making mistakes or the mission's not going well and NASA's embarrassed - then I won't do it.

"But if everything's going smoothly and I want to whack these two golf balls. I'll leave them up there. And I'm going to pay for the golf balls, and the clubhead and there will be no expense to the taxpayer." With that, Gilruth was persuaded, "Okay," he said, "you have a deal." And that was the way it worked out.

After a 40-minute delay because of a rainstorm, Apollo 14 left Cape Kennedy in the afternoon of January 31st 1971, with Shepard, Stuart Roosa and Edgar Mitchell on board. En route to the moon there were three severe technical problems but once on the lunar surface, everything went according to plan.

Towards the end of his second lunar walk, Shepard pulled out the club with the two golf balls. The suit was so clumsy, being pressurised, it was impossible to get two hands comfortably on the handle (of the club)," he recalled. "And it was impossible to make any kind of turn."

So, the shots were made one-handed. According to Shepard, he shanked the first one, which rolled into a crater about 40 yards away. With the second one, however, he kept his head down and the result was a flush contact which sent the ball "at least 200 yards." He said: "The reason I know that, is that I planned to hit it down-sun, against a black sky, so I could follow the trajectory of the ball.

"That happened to be the direction we paced out 200 metres, for our experimental field, and it landed just past that area. Of course I said it went for several miles, which was a slight exaggeration. I folded up the club, with the clubhead, put it in my pocket, climbed up the ladder, closed the door and we took off."

The current issue of the Golfer's Handbook, casts some doubt on Shepard's claim about the distance of the shot. But insofar as the Handbook also suggests that the second shot was the shank, not the first as the astronaut claimed to the USGA, Shepard's version would seem to be the more credible.

And what about the condition of those golf balls, two decades on? According to the man who hit them, they are unlikely to be in any recognisable condition, given temperatures which fluctuate between 250 degrees above zero and 150 degrees below. "I think they've exploded or melted, or a combination of the two," he told Skyzinski.

Before he died on July 22nd 1998, aged 74, Shepard said: "I'll forever be remembered for playing golf on the moon." Indeed he will.