Women have been part of the circus since it was invented by Philip Astley more than 250 years ago. In fact, perhaps we should say invented by Philip and his wife Patty, who was undoubtedly a big part of the enterprise.
Patty played a drum and rode a horse in the first circus ring - with her hands surrounded by a swarm of bees!
The circus was diverse and inclusive centuries before those words came into modern use.
"There has always been a space in the circus where women can be physical," says strong-woman Aoife Raleigh (pictured above). "In Victorian times, women weren’t allowed to show much skin, but if you went to a circus, you would see a trapeze artist with her arms and legs on show. There was a great liberation in the circus."
Raleigh is part of a strong-woman tradition that stretches back to Victorian performers such as Miriam Kate Williams, better known as Vulcana, who flexed her muscles in 19th century music halls.
And yet there are certain circus disciplines such as aerial work where women are a familiar sight, and others, such as clowning, where they are a rarity.
Birkett is the organiser of Daring Dames - Europe's only all-female circus festival - which aims to celebrate not only the role of women in the circus generally, but to put the spotlight on a new generation of women stepping into more traditionally male-dominated areas of the business.
"Even juggling is 80 - 90% men," says Birkett. "Daring Dames has no women standing decoratively, passing the male juggler his clubs."
There are reasons why women gravitate to certain circus skills.
"There are things that female bodies are better at," says Raleigh. "They’re more flexible and lighter and smaller. So they make better flyers."
But why would there historically have been very few female clowns?
"Mainly I would attribute this to the lack of freedom for women in our society," says Francesca Martello, one of the clowns appearing at Daring Dames. "Let's not forget we weren't allowed to vote until last century.
"Freedom of expression and challenging the status quo are very important characteristics of clowning, and that really doesn't go together with the idea that society needed women to portray."
The free-to-attend festival runs from 24 - 26 May and takes over the whole of Achill Island, off the coast of County Mayo in Ireland, with indoor and outdoor, day and evening performances in a variety of venues, including a trapeze rig set up beside the ocean.
While the first two days are geared to public performances, the third day is more industry facing, with a series of talks and discussions on issues affecting female circus artists.
"When women performers get together, there are things particular to them that they discuss," says Birkett.
Herta Fossett, (left) who died recently aged 92, was an example of the multiple roles women play in the circus.
The matriarch of Fossett's Circus began her career in a perch act: she spun in a human-sized hamster wheel atop a pole balanced on her mother's chin.
When she became a mother herself, Herta was persuaded to give up the more perilous big top acts such as high wire, and present elephants. After retiring from the ring, she was in charge of the candy floss stand. She continued to travel with the show and was part of its day to day running until her dying day.
Away from the spotlight, Fossett was also a mother. She brought up the next generation of show-runners and performers, including Fossett's' current ringmaster Marion Fossett.
In a mid-80s TV documentary, Herta said, "The glamour is the two hours that people see. Behind the glamour is the hardship - especially for a woman - which people never realise."
Her chores including carrying containers of water to showgrounds without a mains supply, hand-washing sequined costumes and hoping they would dry in front of the gas fire in her caravan in time for the show.
Not all of today's performers live in travelling circuses, of course. But female performers nevertheless have a different experience to their male counterparts.
"We’ve got sessions on women ageing in circus," says Birkett. "On being pregnant and being a mum when you’re performing.
"We look at costume. Why are men and women’s costumes often so different? Do they need to be?
"It’s a celebration of everything women are doing in circus. It’s very positive, but it doesn’t shy away from the challenges that still exist."
For more information Daring Dames visit www.circus250.com