Sharp and humorous, new BBC Three comedy Britney is a personal triumph for creators Charly Clive and Ellen Robertson, as Danielle de Wolfe discovers.

For many, the name "Britney" conjures up images of a multi-platinum selling pop star, red vinyl catsuits and a hard-fought conservatorship battle.

For actress Charly Clive, it was the decidedly cheerful name given to her golf ball-sized brain tumour.

As initial symptoms sporadically appeared during the summer of 2015, Clive - then 23 and a recent drama school graduate living in New York - dismissed months of missed periods as potential pregnancies. It was only upon her return to the UK the following Christmas that multiple tests revealed a sizable pituitary adenoma - a tumour growing on her pituitary gland which affected her emotions, hormones and vision.

"The MRI had a big brain tumour in it - or rather, my brain did," says Clive, now 28, with a laugh.

Granted, this jovial reaction might not be what you'd expect from a brain tumour survivor, but then again it's not every day that a cluster of multiplying cells forms the basis for a sell-out Edinburgh Fringe show or a subsequent BBC Three comedy series.

Following an operation to remove Britney from her brain, Clive underwent radiotherapy and a stint in intensive care, which saw best friend-turned-writing partner Ellen Robertson, also 28, glued to her side.

It was this experience that saw the duo transform the tale into their hit 2016 Fringe show, with Clive describing the cathartic process as "putting together a puzzle", admitting Robertson's recollection of events surrounding the diagnoses and subsequent surgery were "a lot more accurate" than her own.

"I was in sort of various stages of shock and maybe at times denial," says Clive, who notes she "had a few memory blips" and may have "rewritten my history slightly" as a result of the trauma.

"But Ellen has, I think, a more accurate go of it. In terms of writing, it was quite healing but it was also like 'Thank God!' because we were both able to properly tell each other how it felt and also then go 'How should it feel going forward?' - and that is we want to laugh. We want to have a really good time on stage together. We want people to clap at the end and pay for it."

With the stage show now transformed into a BBC Three series starring its creators, Britney charts a decade of friendship - from a shared moment of transformational theatre in Year 8 Drama Club through to the strain the diagnosis puts on their "co-dependent" relationship.

Describing the series as a "celebration of friendship", Clive says it would be "really counterintuitive" to depict a female relationship where "rivalrous women are pitted against each other" instead of the reality, which is their own "joyful and supportive" experience.

"I think by virtue maybe of drama, a lot of the female friendships we see often have a kind of rivalry at their centre or there's real competition for a man," agrees Robertson. "We just really wanted to tell the truth about what our friendship is like, which, you know, has its moments and is also the most loving and central relationship in our lives."

As if to reinforce their point, conversation switches to the writers' downtime, singling out hit US reality show The Real Housewives Of New York - a programme intrinsically built upon drama - as a go-to source of escapism for the pair.

"What we realised not that long ago is that we don't really like it when they fight," says Clive, who goes on to describe the way in which lead characters Bethenny Frankel and Carole Radziwill get along for a grand total of "half an episode every season".

"It's so stressful," agrees Robertson with a slow exhale. "We like it when they get along - which is never."

Part-time best friend, part-time colleague, Clive says the pair are gradually "getting better" at working together. "I think the danger is always 'Do you do anything else together or do you just become business associates?'" says the actress. "I'll always be one of the first people to read something Ellen's written and vice versa. Because I can formulate my opinion properly when Ellen's told me hers. It's very co-dependent."

As is the case with most personal projects - let alone those involving life-threatening brain tumours - reliving memories can often lead to emotions spilling out at unexpected moments.

Describing the need to "keep pausing meetings whenever one of us would cry", Robertson says the pair became "so used to one of us getting emotional" that production discussions would often continue as though nothing unusual had happened.

"It's a cry to sort of process the thought rather than we need to stop everything and address the person in the room that's crying," says Clive with a nod. "People are terrified of the crying woman. It must be jarring for people that don't do that every day."

Transferring the project from stage to screen meant "using your imagination in a really different way", according to Clive. "When it's just the two of you, you've got to create the whole world in a way. We never had any budget for a set. We had one stool. You had to be really inventive because there was never an option to do anything else."

With Clive describing the "freeing" nature of a production budget which could afford multiple sets and a supporting cast, co-star Robertson says there are also pitfalls which accompanied a transition to television.

"You have to compromise a lot," says the writer. "When you're telling a true story, part of the difficulty I think is killing your darlings. Killing your darlings is one thing, but killing your darlings when it actually happened to you feels slightly more precious."

Despite the gloriously upbeat nature of the pair's friendship, Clive admits Britney's journey from concept to fruition was at times both "challenging" and "unbelievably stressful".

Recounting moments early on where they questioned whether the "needless" pressure was really worth it, Clive says the fear of performing the show to an audience paled in comparison to the real life challenges faced by the duo.

"We can't really get stage fright because we've just been through the scariest thing that you can go through," says Clive, "so doing a stage show in many ways just felt really silly and fun."

- Britney airs on BBC One and will also be available to stream on BBC iPlayer from Tuesday November 30.