Bradman, at 54, was playing his final match, returning to the game at the request of Robert Menzies to captain the Prime Minister's XI against the MCC.

Mr Scheeren, a Year 5 pupil at Canberra Grammar School, was determined to get one of the cricketers' signatures on his brother Jan's bat.

The fact he was on crutches because of polio was a mere trifle for a young boy trying to capture a little of his heroes. Not even a fence ''about six inches high'' could stop him.

''My brother was having no luck getting his bat signed, so I jumped the fence and knocked on the players' door. It was a huge surprise that the greatest cricketer of all time answered that knock,'' he said.

Bradman signed the bat and the photograph of their meeting ended up in the National Archives of Australia years later.

Mr Scheeren, now 55 and living in Queanbeyan, returned to Manuka Oval yesterday to help launch a collector coin issued by the Royal Australian Mint to commemorate today's 100th anniversary of Sir Donald's birth in Cootamundra.

Sir Donald died in 2001 aged 92.

''I think it's sad that Don Bradman can't be here for his 100. I'm sure he's playing cricket in heaven at the moment,'' Mr Scheeren said.

Royal Australian Mint chief executive Janine Murphy said the $5 uncirculated Bradman coin commemorated his ''greatest century of all''. It was designed by Vladimir Gottwald and would be sold by the mint for $18.75.

''It depicts the familiar pose of the Don, holding his bat in the air, saluting the crowd after making one of his 211 centuries.''

The coin will feature at tonight's Sir Donald Bradman Centenary Dinner in Sydney.

Yesterday's launch in Canberra was also attended by Cricket ACT chief executive Mark Vergano and president John Gallop.

Mr Vergano said the new Bradman coin would be used for the toss at the next Prime Minister's XI match at Manuka.

''For all our successes at things like the Olympic Games and on our sporting fields around the country, it's a cricketer who played his last match over 40 years ago, here at Manuka; over 50 years since his last competitive match, and he is still synonymous with sporting success,'' he said.

''That really says a lot about the person and the place he holds in Australian culture.''

Mr Gallop met Sir Donald twice and cherished each encounter with his favourite sportsman. ''He's just the greatest cricketer ever,'' he said.

And, sadly, that cricket bat signed by Bradman was lost when the Scheeren family moved to Canada some years later, presumed stolen en route.