The full extent of King Edward VIII's racist attitudes to Aboriginal Australians have been revealed in a new documentary detailing letters he wrote to his mistress.

The correspondence shows the then-Prince of Wales ranting about having to see 'filthy, nauseating creatures' as he met Aborigines during his tour of 110 cities across Australia in 1920.

The letters to married English socialite Freya Dudley Ward show a different side to the one he portrayed in public during the tour.

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Racist letters about Aboriginal Australians from the future King Edward VIII (pictured) have been unearthed in a new documentary

She was the future King's lover from 1918 to 1923 and they remained close until 1936, when he met American divorcee Wallis Simpson, whom he gave up the throne for later that year.

In public the heir to the throne appeared to be a benevolent royal, showing sympathy to Australian soldiers who had served in the Great War, University of Sydney Royal Historian Dr Cindy McCreery said.

He was extremely popular during his visit and was affectionately dubbed the 'Digger Prince' by Australians because he served during the First World War.

But in private, the 25-year-old complained about having to see 'revolting black savages' as part of his tour.

The letters are stored in the New South Wales State Library and were unearthed for the ABC documentary The Crown and Us: The Story of The Royals in Australia, which aired on Sunday night.

In a letter dated July 16, Edward VIII, who was on board a ship from Adelaide to Hobart, excitedly wrote about the prospect of not having to see more Aboriginal demonstrations.

'The press have been hinting I'm too soft to be able to rough it on a real up-country station, which I've not had a chance of doing yet,' he said.

The correspondence shows the then-Prince of Wales ranting about having to see 'filthy, nauseating creatures' during his tour of Australia in 1920 (pictured)

'I ought to see that very important side of Australian life and it will be of far more value than seeing a crowd of revolting black savages who don't yet know whether they are British or Hun, and care less.'

In another excerpt dated July 11, he called Aborigines 'the lowest known form of human being and the nearest thing to monkeys I've ever seen.

'They showed us some of the native Aborigines at a wayside station in the great plain yesterday afternoon, though they are the most revolting form of living creatures I've ever seen,' he said.

In public the heir to the throne (pictured during his visit) appeared to be a benevolent royal, showing sympathy to Australian soldiers who had served in the Great War, University of Sydney Royal Historian Dr Cindy McCreery said

'They danced for us and threw spears and boomerangs, though the interest of this native stunt - and you know how I just loathe any form of native stunt, sweetie was spoilt by the fact that they had all been transported, vermin and disease and all.'

In one of the letters he criticised authorities for bringing him Aboriginal representatives who 'looked like they had just drifted in from a waterless district'.

Edward spent 49 days conducting royal duties in Australia, which included visiting Victoria, Queensland, New South Wales, South Australia, Western Australia and Tasmania.

Married English socialite Freda Dudley Ward (pictured) was the Prince of Wales' mistress

He was extremely popular during his visit and was affectionately dubbed the 'Digger Prince' by Australians because he served during the First World War.

Other letters written to Freda Dudley Ward during his 1920 visit to Barbados show a similar view to those he wrote while in Australia.

He reported the country as being 'ugly' and he found the 'coloured population' to be 'revolting'.

A new documentary titled The Crown and Us: The Story of The Royals in Australia has shed new light on the royals (Edward VIII pictured while Governor of the Bahamas in the 1940s)

He also wrote of begrudgingly dancing with various women on the trip, all of whom he insisted had to be young and vetted by his friend, Louis Mountbatten.

Edward VIII, the eldest son of King George V and Queen Mary, would go on to become King of England in January 1936.

He abdicated in December of that year in order to marry American divorcee Wallis Simpson.

'They are the lowest known form of human beings & are the nearest thing to monkeys I've ever seen,' Edward VIII wrote of Indigenous Australians