They were on the buses on what was known as Conversion Day or "C Day" when pounds, shillings and pence were replaced with dollars and cents.

Both men were bus drivers in Canberra and from early in the morning had to deal with passengers who were paying in the old currency and receiving change in the new.

Mr Walters, 75, of Watson, remembers there was a period of grace for all concerned but it was still a little stressful dealing with all these new notes and coins.

"There was a lot of, 'Am I giving the right change? Am I getting the right change?'," he said.

"But we were allowed to make some mistakes and so were they."

Mr Redman, now 87, of Ainslie, remembered the barrells of the change machine had to be altered to account for the size of the new coins. The Retired ACT Transport Employees Club, of which the men belong, still have both versions of the change machines in their little clubhouse in Campbell.

"People had the option on the day. If they didn't have the new currency, they could pay with the old," he said.

By chance, Pat Torpy, now 79, of Dickson, was sitting his exam to become a bus driver on the very day of February 14, 1966. He remembered his good mate, Mr Walters, staying up with him until the early hours of the morning tutoring him on the new currency.

But when he got to the exam room, Mr Torpy had to admit to his supervisor "I don't understand this bizzo".

He was allowed to go on a planned holiday to Queensland and upon his return, and with some breathing space from the introduction of decimal currency, passed his exam.

Another Canberran who remembered the introduction of decimal currency – with its 50th anniversary falling on Sunday – was Ainslie IGA owner Manuel Xyrakis. He was 11 at the time, working after school in the same supermarket, then owned by his parents.

"I remember a lot of people getting a bit confused. There were 12 pence in a shilling and suddenly they were getting a 10 cent coin and though they were being short-changed two pence," he said, with a laugh.

Canberra author Peter Rees said for all the logistics required, Australians handled the change – literally – remarkably well.

The switch cost the then government $45 million – under the budgeted $60 million.

When the Royal Australian Mint opened in Canberra in February, 1965, its first task was to produce the 1c, 2c, 5c, 10c, 20c and 50c coins ready for the introduction of the new system a year later.

The Reserve Bank printed 153 million new currency notes – the $1, $2, $10 and $20.

Mr Rees said the operation to get the money into banks was worthy of a Hollywood script with lorries full of cash criss-crossing the nation in a secret campaign called Operation Fast Buck, no less. Commonwealth Police accompanied the trucks with Owen submachine guns, he said. Local police also augmented the security.

A public education system, led by the animated character Dollar Bill and a jingle to the tune of Click Go the Shears, readied the populace for the change.

"There were a few grumbles but by and large people coped," Mr Rees said.

"I think also the fact the coins were so beautiful, Stuart Devlin's designs were so beautiful, that people embraced the coins. They were a vibrant representation of post-war Australia."

Some of the coins have since gone by the wayside. The 1c and 2c coins were scrapped and some actually melted down for bronze medals at the 2000 Sydney Olympics.

And for all the talk about a possible dumping of the 5 cent coin, Assistant Treasurer Alex Hawke said this week there were no such plans. Despite the rise of electronic transactions, half of transactions conducted in Australia were still done so in cash.

"There's no plans in the future to change that," Mr Hawke said.

The Royal Australian Mint is celebrating the 50th anniversary of decimal currency with the issue of special coins throughout the year and an open day on Saturday.

The Mint's CEO Ross MacDiarmid said it now produced about 200 million pieces a year for circulating coins in Australia.

"The commemorative coin we're releasing is actually a combination of the old and the new," he said.

"We've actually got the image of the old pound, shilling and pence appearing on each of the decimal currency coins. They will go into general circulation in limited quantities starting with the 50 cent piece from Monday."

And the Queen is still there.

"She's definitely there, just in a smaller version," he said.