"The movie tries to cover both grounds," Dancy concedes. "There's the comedic aspect of having these doctors up inside women's skirts as well as the seriousness of the fact that the women were being completely misdiagnosed."
In this fictitious yarn directed by Tanya Wexler, the 37-year-old actor is the buttoned-up Dr Granville who joins the women's medicine practice at the surgery of Dr. Dalrymple (Jonathan Pryce) who offers pelvic massages as therapy. Only Mortimer soon becomes overworked too and finds a solution to relieve his aching forearms via his inventor friend, Edmund St. John Smythe, played with over-the-top verve by Rupert Everett.
"Rupert's a comic distraction to some degree," Dancy admits. "In the story my parents died when I was young and I was kind of taken on by Edmund's wealthy family. He has too much time and money on his hands so he's tinkering with electricity and newfangled things. He invents an electrical feather duster which by process of elimination becomes the prototype for the vibrator."
While Dancy is the straight man of the piece (the film's writers, Stephen and Jonah Lisa Dwyer, based him on a young Hugh Grant) comic star Pryce manages to be hilarious in his role as an upstanding member of the medical establishment. "We played the treatment scenes as straight as possible and I think the more serious we were in playing them, the funnier they became," Pryce notes. "Playing it very straight when extraordinary things are happening is a well-known key to comedy."
The film's writers had a young Hugh Grant in mind when writing Dancy's character; for Dr Dalrymple's suffragette daughter played by Maggie Gyllenhaal, they were thinking of Katharine Hepburn.
With her piercing blue eyes and the sweetest of husky voices, Gyllenhaal musters all her tomboy charm - and an English accent - to put the stuffy men of the medical establishment in their places.
"The movie is about a lot of things, but you do get to see a lot of women having orgasms - and that's the shocking thing," she says of a film which invariably has women laughing nervously and squirming in their seats.
"It's not really about whether or not woman have vibrators as much as whether or not they have orgasms. And whether or not you can talk about it."
"The comedy grew out of the fact that this really did happen," notes director Wexler. "Yet if we started injecting actual historical characters in a comedic way it would have moved over to farce and there would have been a lack of believability.
"We wanted the movie to make audiences sit forward; we wanted to draw them in. So we created characters we really liked and we wanted to see their story told but we wanted to have a political agenda as well.
"The reaction has been astonishing," she adds.
"It just shows the paucity of information out there. And what is truly subversive is that it's a movie you can bring your mum to!"
It's a talky kind of movie, reminding of a Victorian spin on the Hollywood screwball comedies of the 1930s and 1940s.
"In some scenes Hugh and I would have tons of dialogue and it was important to make it have that fast paced romantic comedy feeling," says Gyllenhaal.
"We'd be walking through a party and dropping off a champagne glass and picking up something and turning and going over here while we were talking, talking, talking, talking. Because of the style of the movie, if the rhythm was off, you'd have to start the scene again. Actually I think it was technically really difficult."
Gyllenhaal says she was awash with gift vibrators from friends by the end of filming - including one from her director.
American Wexler gave everybody on set one, which meant taking them with her to Britain. But getting them there caused embarrassment for a security guard at Heathrow airport.
Remembers Wexler: "The officer said, 'You have 20 or 30 small electronic devices in your luggage,' and I said, 'Yes, they're vibrators,' and the guy just said, 'Move along'."
What: Hysteria starring Hugh Dancy and Maggie Gyllenhaal
When: Opens at cinemas Thursday with sneak previews this weekend
- TimeOut, Additional reporting AFP