Nearly exactly a century ago, Ross and Keith Smith departed England on one of the most ambitious flights in aviation history.

The two South Australian brothers were competing for a £10,000 prize offered by then Australian Prime Minister Billy Hughes to the first team in a British-made aircraft to make it from London to Australia within 30 days.

They would go on to make history, landing in Darwin on December 10, 1919 less than 28 days after their departure. The daring accomplishment was unlike anything ever seen at the time and has since been credited as a major turning point in global aviation.

But there is a forgotten chapter to this story.

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Captain Cedric Ernest Howell was a fellow South Australian and decorated war hero who ultimately fell on the wrong side of history, launching his own doomed race attempt on December 4, 1919.

SUPPLIED Photograph of England-Australia flight. Ross and Keith Smith, and Wally Shiers at Cobbs Creek, Northern Territory sometime between 14-17 December 1919.

The exact circumstances surrounding his death, and that of his co-pilot Lieutenant George Henry Fraser, off the coast of Corfu just five days later would never be known.

According to the Australian War Memorial, their Martinsyde A1, G-EAMR aircraft was spotted flying in the dusk sky over St George's Bay on December 9, about 13 hours before the Smith brothers landed in Darwin on the other side of the world.

A local innkeeper said the aircraft circled the bay four times, presumably to find a landing space, but crashed in the water less than 300 metres from shore.

He heard the two men calling for help but the sea was too rough for him to venture out on his boat.

Captain Howell's body washed ashore several days later but Lieutenant Fraser's body was never found.

The death hit Captain Howell's father Ernest hard.

He wrote a 14-page letter calling for an inquiry while also making explosive allegations against the race organisers.

Howell's main claims centred around a decision by organisers to postpone the earliest date at which teams were able to start their race attempt, as well as subsequent delays forced upon his son and Lieutenant Fraser.

Former Nasa astronaut Andy Thomas, who carried Sir Ross and Sir Keith's badges with him into space, told AAP it was natural for parents or spouses to raise questions after aviation tragedies.

"The same thing happened with the two shuttle accidents: Challenger in '86 and Columbia in 2003," Thomas said.

"It's a way of achieving emotional closure.... I think that's kind of universal when there's an unexpected accident," he said.

Howell's letter also stated that the prime minister had ordered certain alterations to be made to competing aircraft, under the guise of new safety requirements.

He also claimed special favour was given to Sir Ross, citing "the fact that the payment to competitors ... for the delay ... was stopped the day the Smiths left England".

Adelaide resident Robert James Mackenzie, 72, whose grandmother was Captain Howell's sister, says he hopes to see more recognition for all the competitors.

"They were all very brave men - it's not until you read (about it) that you realise how hard it was; they were freezing up there, they had open cockpits and the only plane that was closed crashed five minutes after leaving England," he said.

"They proved to the world that long flights were possible."

SUPPLIED Presentation of a cheque for £10,000 to Ross Smith, by Prime Minister W.M. Hughes after the first successful flight from England to Australia.

Sir Ross responded to Howell's accusations, writing a letter to the government denying a number of the claims.

"I need hardly say that there is absolutely no truth or foundation for these charges," Sir Ross wrote.

"I make every allowance for Mr Howell's grief and mental disturbance due to the tragic loss of his son and have no wish to punish him by the bringing of a libel action against him."

The Department of Defence provided a statement refuting many of the most damning allegations, but it did not examine exactly what caused Captain Howell and Lieutenant Fraser's aircraft to plummet into the sea off Corfu.

Thomas said it was unlikely the full story would ever be known, including whether Sir Ross influenced the date of the race.

"It was certainly true that Ross Smith had a lot of influence and a lot of friends in high places, and you could well imagine a scenario where that might have been the case, but we will never really know for sure," he said.

Regardless of the dispute, there's wide consensus that Sir Ross and Sir Keith well and truly won the race on merit, thanks to meticulous planning and clever decisions.

When it came to race time, Sir Ross chose to carry two mechanics with him, stopping each night to thoroughly clean the Vickers Vimy's two engines.

Sir Ross died in April 1922 while testing a Vickers Viking amphibian at Brooklands, England, in preparation for an around-the-world flight.

Witnessed by his brother Sir Keith on the ground, the aircraft crashed, killing Sir Ross and mechanic James Bennett. An inquest later labelled it "death by misadventure".

No such inquest was held for Captain Howell, a Distinguished Flying Cross recipient.

Carolyn Spooner from the South Australia State Library, who spent more than a year curating an exhibition for the 1919 air race centenary, said she hoped more people would come forward with information about Captain Howell.

"Cedric Howell was a very sad case," she said.