An Australian World War II veteran's long campaign to clear a slur against his air crew is finally over, after United States Navy historians sent him a letter clearing him of not alerting the Americans that Japanese ships were heading towards Solomon Islands.

Last year, 7.30 told the story of Eric Geddes, who served as radio operator and gunner on an RAAF Lockheed Hudson based in Milne Bay, New Guinea during WWII.

On August 8, 1942 his crew spotted and reported a Japanese attack fleet heading towards the US Marines force that had just landed at Guadalcanal.

Sorry, this video has expired World War Two veteran finds justice after 70-year battle ( Adam Harvey )

That night, the Japanese went on to rout Allied ships off Guadalcanal, sinking four cruisers, including the HMAS Canberra, killing more than 1,000 sailors.

The battle of Savo Island, as it became known, was the Allies' worst naval defeat of the war.

An influential US historian, writing after the war, falsely accused Mr Geddes and his crew of failing to promptly report their sighting.

In his 15-volume account of the US Navy's World War II actions, Rear Admiral Samuel Morison wrote: "The pilot of this plane, instead of breaking silence to report, as he had orders to do in an urgent case, or returning to base which he could have done in two hours, spent most of the afternoon completing his search mission, came down at Milne Bay, had his tea, and then reported the contact."

The implication was that the Australian crew's tardiness contributed to the effectiveness of the surprise Japanese attack.

Crew actually sent message while under attack

Rear Admiral Morison's account was baseless: Mr Geddes had immediately transmitted the sighting of the Japanese flight.

He sent the message "in clear" while the Japanese turned their attentions onto the Hudson crew.

"They sent up two fighters to take care of us," Mr Geddes recalled.

"We thought we can't stand and fiddle around with these people. We've got to deliver this intelligence.

"I got on the radio and tried to contact Milne Bay."

The proof was not just that Mr Geddes' message was picked up by Australian radio operators.

It was heard by the Japanese themselves, who recorded the intercept in their own military archives.

Crew wrongly blamed for more than 1,000 deaths

Rear Admiral Morison's account was published in 1949 and was immediately picked up by newspapers around the world, including in Australia.

Eric Geddes

"If I printed in tomorrow's newspaper that you were responsible for the deaths of 1,023 sailors, how would you feel?" Mr Geddes asked.

"We were angry and couldn't believe that this could be. We just couldn't believe it."

Australian historians later discounted Rear Admiral Morison's claims, but the false version stands uncorrected in the US.

"It was the American people who were fooled," said Mr Geddes, who is now in his 90s and has been fighting for 65 years for the record to be corrected.

"Now, why would I settle on something here in Australia when the victim was in America, and the American public, they're not aware of what the truth was."

Canberra-based historian Dr Chris Clark, who worked with Commodore Bruce Loxton to write a book about the naval disaster, said Rear Admiral Morison's account was unsourced and wrong.

"I don't know where Morison got his information from," Dr Clark said.

"It's a pretty hard falsehood to tell against the RAAF pilots, or the RAAF crew, and to put it in print, in a form that really lasts a long time, and it's very hard to retract once it's in print."

Mr Geddes even wrote to US president Barack Obama in an attempt to clear the name of the Hudson crew.

7.30's original story set in train a series of events that have now led to Mr Geddes receiving a letter from US Navy historians, thanking him for his war service and criticising the account of Rear Admiral Morison.

Former RAAF chief took up cause

The letter is thanks to the efforts of his former RAAF colleague, Air Marshal David Evans.

Air Marshal Evans flew with Mr Geddes in the 1960s and rose to become the RAAF's chief of the air staff.

But the first he knew of the Hudson scandal was when he watched 7.30's report.

"I was astounded, I rang him up straight away: 'why didn't you get in touch with me before?'"

"He said, 'you don't like to burden'.

"I said, 'you damn fool'."

The former chief of the RAAF began his own campaign.

Thanks to his connections, there has been action within the US Navy.

US letter vindicates wronged crew; Eric Geddes is lone survivor

Mr Geddes received a letter from the Naval History and Heritage Command, within the US Department of the Navy.

It contains these vital lines: "A new generation of naval historians is questioning previous works, such as that of Rear Admiral Samuel Eliot Morison, often written too close to the end of a recently completed campaign ... RADM Morison's criticism, in particular, was unwarranted."

The letter is from Greg Martin, the assistant director of the US Naval History and Heritage Command, in Washington.

"I wanted to be able to assure him that there's a lot of history out there that provides a very different take and interpretation of events regarding the Hudson and sightings," Mr Martin told 7.30.

Mr Geddes said he was satisfied with the carefully-worded letter, which proves he was right all along, and stands as a validation of his crew-mates.

The last survivor of the Hudson crew has just one regret.

"Unfortunately, the wrong thing happened to Morison. He died. I would like to be talking to him," he said.