Florence Foster Jenkins's costumes were almost as outrageously strange as her voice. When director Stephen Frears needed someone to recreate them for the film, he turned to fêted costume designer Consolata Boyle

When audiences in their thousands paid for tickets to witness the wonder that was Florence Foster Jenkins, it was more than the horrendous singing they were shelling out for. There were the astonishing costumes too.

Jenkins’ bizarre creations, all of her own design and manufacture, included eccentric approximations of a Mexican señorita, an 18th-century ball gown, and timeless audience favourite the “Angel of Inspiration”, featuring a gargantuan pair of heavenly wings which she would don before awkwardly drifting about the stage.

Too much never being nearly enough, Jenkins would accesorise enthusiastically, perhaps with a dainty parasol, which she twirled with all the grace of a Glasgow hod-carrier, or giant ostrich feathers with which she violently fanned herself.

It was a sight to behold. And when it came to recreating Jenkins’ catastrophic couture for his biopic, Florence Foster Jenkins, director Stephen Frears had only one woman in mind: legendary costume designer Consolata Boyle.

“Consolata is simply brilliant,” the director says of Boyle, with whom he has worked on numerous projects, including The Van (1996), Philomena (2013) and The Queen (2006), for which she gained an Oscar nomination. “I barely need to speak to her as I know what she’s doing is going to be dazzling. I’ve worked with her for 25 years, so I’m very lucky.”

“I was fascinated and enthralled by the character of Florence,” says Boyle. “And the story is about something I find really important, a love story between three people who love each other in particular ways, but also about the transformative effect of music. The simplicity of that thought was what I held on to, and everything else followed on from that.”

After studying history and archeology at college, Boyle trained in set and costume design at the famous Abbey Theatre in Dublin before making her debut as costume designer on television drama The Irish R.M. in 1983. “It was absolutely terrifying,” she recalls. “I was thrown in as a full designer, and I’d never even been an assistant. It was an extraordinary learning experience.”

Subsequently she worked on high-profile films such as Mary Reilly (1996), Angela's Ashes (1999) and Testament of Youth (2014). But the job of dressing star Meryl Streep – with whom she had worked previously on The Iron Lady (2011) – as the fashion-blind chanteuse presented challenges all of its own. These included adding more than a few pounds of padding to Streep’s slight frame in order to recreate Jenkins’ more matronly outline.

“I worked incredibly closely with Meryl every step of the way, we had a lot of discussion early on about how she would express her inner emotions in her clothing,” she says. “But it’s like starting from scratch even if you’ve worked on the period before.

“Jenkins’ extraordinary eccentricities and her coterie were a very particular thing; she lived and thrived in a very sealed off world,” Boyle continues. “She dressed the same as she had as a girl, before the various tragedies and darknesses affected her life. Her costumes were like her childhood dressing-up outfits, so everything was in very childish colours.”

But despite her crimes against fashion, Boyle, like audiences nearly 100 years ago, can’t help but admire the redoubtable Jenkins.

“She was a supreme performer, so her clothes were gorgeously outrageous,” she marvels. “They were high camp but with a softness so she drew people in. And she had no embarrassment about how she looked.”

• Florence Foster Jenkins is released on 6 May 2016