The former AIF captain can recall sayings from generations ago in languages from German to Japanese and Malay.

But in an interview with a historian for the Australian Intelligence Corps earlier this year he realised he could not recall where his many medals from World War II were.

This information found its way to Australia's Chief of Army, Lieutenant-General Angus Campbell, and on Saturday the chief solved the problem with a rare personal delivery of replacement medals to Mr Lederer's Curtin home.

"It's the proudest day of my life," the English-born centenarian said.

The oldest known surviving Australian World War II electronic intelligence specialist regaled Lieutenant-General Campbell, a small military entourage and family and friends with some of his adventurous life and crucial translation work.

Born to an Austrian father, who was a successful cotton businessman and once consul-general to the United Kingdom, Mr Lederer's fluency in German led him to be assigned to a special wireless unit where his translation skills were used against the Germans, Italian and Vichy French in North Africa and Lebanon.

First arriving in Australia in the 1930s, he returned with his unit in 1942 and was assigned to General Douglas MacArthur's top-secret Central Bureau Intelligence Corps, being sent to Moratoi in New Guinea to monitor and translate Japanese radio transmissions.

This unit gathered critical intelligence for the future Allied victory in the Battle of the Coral Sea and General Macarthur's liberation of the Philippines.

Lieutenant-General Campbell, who spent more than an hour with Mr Lederer on Saturday, said it was an honour to recognise his service and give back his medals.

"He and his generation were instrumental in building and protecting the nation that we now have the privilege to live in," he said.

Mr Lederer was also presented, for the first time, the Australian Service Medal with clasp "SW Pacific" 1945-75.

After the war ended he became an immigration selection officer in north Germany, screening thousands of Europeans who wanted to come to Australia.

He previously told Fairfax Media his greatest achievement was "picking one for myself", a beautiful Lithuanian girl called Tina who has been his wife for the past 66 years. The couple moved to Australia in 1951 and have lived in their Curtin home for 44 years.

Mr Lederer was not the only skilled linguist in the family, with his late brother, Rudi, a translator for the Queen, Winston Churchill and Margaret Thatcher during his long career.