George and Willie Muse had been born albinos and were known as the Sheep-Headed Cannibals.
The extravaganzas staged by Bertram Mills at London's Olympia every Christmas were events to see - and be seen at. George V and Winston Churchill were among a legion of VIP fans.
No wonder the celebrated showman was under pressure to find ever more unusual circus acts with which to titillate the crowds each year.
Wonders such as Paul Leinert, the Human Cannonball, and Koringa, a "female fakir" who hypnotised alligators, were popular. But those who packed his 6,000-seater big-top always wanted something new.
So, in 1928, Mills asked James "Candy" Shelton, a U.S. freak show operator, to send over two brothers who were among the biggest sensations of their day.
Variously known as The Sheep-Headed Cannibals, The Ambassadors From Mars or the Ecuadorian Savages, their real names were George and Willie Muse and they had been born albinos.
Their bodies were unable to produce skin pigment, giving them the features of their African-American parents but white skin, golden hair and pink-tinged blue eyes.
In their early 30s when they arrived in London, they had been forced by Candy Shelton to wear their hair in long, white dreadlocks to make them look even more exotic.
A newspaper claimed their wild locks grew so woolly and so quickly the trimmings could make the equivalent of three woollen shirts a year.
The Muse brothers were, indeed, the centre of attention at the annual lunch Mills held to give the great and good of London society a preview of that season's circus attractions.
In fairness to the London audiences who saw them perform, they knew nothing of the brothers' origins, their tragic story - or the reason for their life-long obsession with the music hall favourite It's A Long Way To Tipperary.
This was a song they sang as part of their act, accompanying themselves on the banjo, guitar and xylophone. But they also performed it endlessly in private, identifying with the theme of longing for home that made the ballad so popular with soldiers in World War I.
Now, a new book tells the bittersweet tale of the Muse brothers, of their kidnap and decades-long exploitation - and of their mother Harriett's desperate search for them.
The nightmare began on a sweltering day in 1899, as George and Willie Muse, draped in rags to protect their sensitive skin, worked in the tobacco fields near their home in rural Virginia.
Looking up they saw a white man approaching. The presence of a well-dressed stranger in this hodge-podge of dirt roads, tobacco barns and shacks where tenants stuffed newspapers into holes in the walls to keep insects out was unusual enough.
It was even more of a surprise to find out that he had come specifically to see them.
Nobody knows how Robert Stokes found out about the albino boys, then aged six and nine, the sons of an illiterate washerwoman in the remote settlement of Truevine, where everyone was a former slave or a child or grandchild of slaves.
But there was no hiding the fact that the brothers were different - and Stokes, who ran a touring freak show, saw instant profit in their colouring and features.
Harriett, struggling to bring them up alone, barely had enough to feed them and they were always hungry.
When they complained that their stomachs were rumbling, she sometimes gave them tobacco leaves, an appetite suppressant, to chew. Stokes had only to offer them sweets to persuade them into his horse-drawn carriage.
Within seconds they were gone, kidnapped into a life of subjugation as sideshow freaks. When her sons had failed to come home by sunset, their mother panicked.
She told friends she knew something was desperately wrong, but the disappearance of two little boys was of no interest to the local police and she was left to make her own inquiries.
When she heard that a white man in a carriage had been spotted roaming the area that day, it didn't take her long to work out what had happened.
Bounty hunters were known to scour the U.S. for people they could turn into sideshow attractions, such as the Wild Men Of Borneo - a pair of dwarf brothers from a farm in Ohio.
But there was little Harriett could do to prove her suspicions.
By the turn of the century, there were around 100 travelling circuses in America, each traversing thousands of miles as they competed for the best pitches. Her sons could be anywhere.
She never gave up hope of finding them, asking neighbours and fellow church-goers to alert her whenever they heard of a circus performing nearby.
As for the boys, they were swallowed up by a world in which sideshow acts were on call all day long, with impromptu extra performances whenever their manager had lured enough people into the "odditorium", as the canvas confines of their tent were known.
Their fellow performers included Miss Astoria Gibbons, a woman with a huge tattoo of the Last Supper on her back, and Mr and Mrs Tiny Mite, the Smallest Married Couple In The World.
The sideshows were intended to inspire equal measures of awe and wonder and horror.
They also made spurious claims to be educational. A lecturer walked from one act to another, giving a short introduction before the "freak" in question would demonstrate their special skill.
In the early days, the boys did little except submit to the onlookers' curious gaze and speak the occasional bit of gibberish.
Sometimes they were billed as Darwin's Missing Links; at others, as Nature's Greatest Mistakes.
Their origins shifted constantly from one circus season to the next. They had been discovered floating on a barge in the Gulf of Mexico. Or down the Amazon. Off the coast of Madagascar. At one point, it was even claimed they came from Mars.
In short, they were cast as anything but what they actually were: two desperately unhappy little boys who cried each night as they lay in their lice-ridden bunks for a mother they were told was dead.
To earn money for themselves, they were forced to carry water, do chores and laundry.
They were illiterate and their slowly worsening eyesight, a complication of albinism, made them ever more dependent on those who exploited them. George and Willie Muse were, in effect, slaves hidden in plain sight.
And their chances of fleeing the sideshow lessened still further when it was discovered that they could sing well and had an aptitude for playing musical instruments.
By the Twenties, their striking appearance and musical talents placed them among the elite of "freaks".
Dressed in matching sports jackets, with impeccably shined shoes and flat caps - the latter removed with a flourish to reveal their shocks of white hair - they were exhibited as part of the world-famous Ringling Bros and Barnum & Bailey Combined Circus, otherwise known as The Greatest Show on Earth.
Each year it played to as many as two and a half million people in 125 cities and towns across the U.S. and the brothers' success made them ever more valuable to Candy Shelton, who had bought the brothers from their kidnapper Robert Stokes.
A canny and unscrupulous operator, Shelton was making today's equivalent of £350,000 ($626,000) a year from the brothers.
Of that they saw not a penny - but that was all about to change.
In 1927, the circus arrived in Roanoke, a city just 30 miles away from Truevine. George and Willie's mother Harriett, who had married Cabell Muse and had three more children, had moved there in search of work.
When she heard about the albino brothers, she knew instantly who they were - and decided to claim them back.
Her strategy for doing that was bold. Though there was no "Whites Only" sign at the Roanoke Fairgrounds, it was the venue where the local Ku Klux Klan rallied.
Black people knew they could not wander the show grounds at will without risk of arrest or even lynching.
Harriett paid little heed to that, finding a place near the back of the crowds as they were guided from one sideshow to the next.
The brothers did not see her at first as they sang It's A Long Way To Tipperary. But halfway through, they spotted her, at which point chaos ensued. "Look! There's our dear old mother," cried George. "Look Willie, she's not dead."
They rushed from the stage into her arms. When Candy Shelton turned up to see what was disrupting his show, she stared at him in defiance.
"They are MY children!" she said. "Can't no white man birth two coloured children."
And she did not flinch when eight policemen converged on the tent, along with Ringling executives in suits and fedoras.
"The Ringlings are powerful," they reminded her. "They're multi-millionaires who have the ear of presidents, their own railway lines and mansions in several states."
Her dusty shoes planted firmly in the sawdust, Harriett refused to budge.
Eventually, the police told Shelton that the Muses were free to leave with their mother if they wished.
They did wish. And within a few minutes of the brothers arriving home with Harriett, huge crowds gathered to get a glimpse of them.
Their stepfather Cabell Muse immediately began demanding an entrance fee for any gawkers who wanted to traipse through the house.
A brutish man, he threatened to be every bit as exploitative as Candy Shelton and, for all that they loved their mother, the brothers felt unable to live alongside him in the ramshackle home where they had even less space than on a circus wagon.
Soon they went back to the circus - but on their terms, or those negotiated by the lawyers hired by Harriett on their behalf - to continue with their careers, but as well-paid stars rather than exploited "freaks".
They toured for many more years, decked out in Hawaiian shirts on jaunts around the island resorts of the Pacific and were treated with at least a modicum of respect in contrast to their early lives.
They regularly went home to see their mother, and she ensured Candy Shelton and subsequent managers paid the brothers their due.
Whenever cheques bounced, as they often did, she dispatched her lawyers and payment was quickly forthcoming.
The LAWYERS continued to represent Willie and George long after Harriett's death in 1942.
When the brothers finally retired in the Sixties, they had enough savings to buy the house in Roanoke in which they lived together until George died of heart failure in 1972.
Willie grieved hard, but he did not die of a broken heart as his family had feared.
He lived another three decades, passing away in 2001 at the age of 108 surrounded by his beloved collection of stuffed toys, music boxes and snow globes which he had amassed over the years - his way of living out the childhood that he and his brother never had.
Truevine: An Extraordinary True Story Of Two Brothers And A Mother's Love by Beth Macy (Macmillan).