Happy birthday Ruby,” I say, proud of remembering such an iconic date. “Doing anything nice?” I ask..... “Working on the show,” she replies curtly.

“What about tonight then?” I proffer. “Working on the show,” she repeats.

“I’m sure the kids will make a fuss of you later,” I try, wincing in anticipation. “They are grown up now and can fend for themselves,” she retorts.

OK then, no more Mrs Nice Guy. And if not Nice at least funny or wordy would help.

Ruby Wax was the sharp-tongued, sharp-witted, brash American comedienne who has been a favourite on television screens since the late 1980s. She’s better known in the UK, where she has lived for many years, than in her native USA.

You might remember her TV missives Ruby’s American Pie, Wax Meets… and Hot Wax?

And now she’s back, but not as you know her. Gone is the clown of yesteryear. In her place is a sterner, more honest version who claims she has reinvented comedy with her new show Losing It, which she has already toured around 13 Priory clinics, and is bringing to the Oxford Playhouse on Monday.

And yet, as a former interviewer, she sucks in the hotseat, refusing to chat, spitting out responses with the venom of a caged animal.

So why now? Why is she back so many years after she disappeared from our screens in a cloud of smoke, rumours of depression and a bipolar disorder abounding?

“It’s the first time in 11 years I’ve had something to say,” she admits.

Is that because she’s been busy bringing up her children? “Maybe subconsciously. But it is really exciting because I’ve always loved to reinvent stuff, I did it with TV and now I’m doing it with comedy. We just have to see if people like it. It’s funny but it’s dark.”

So is it more you? “Well, what is you? It’s certainly not who I was before because that’s not that interesting. This is more of a 360 degree view rather than knowing what’s coming because that’s the problem with comedy; you get it, and you get it, and you get it, and then you know what’s coming and it stops being funny.

“But I think Losing It will surprise people and for me it’s more pleasurable because I don’t have to work so hard. There is no persona. I’m not working behind a mask. I stopped before because I felt the act was beginning to lose it’s lustre. So now I don’t feel as if I’m flogging my soul. Some people say how can you be that honest? But it’s normal for me. I’m not doing it naked!”

And yet Losing It, in her own words, is based on her studies of neuroscience. “So part of this is like a funny version of my masters. When we go through life, we don’t have an instruction manual. So when you become a mother or father or teenager, you can sometimes feel like an outsider. And you need some sort of guide as to how to fit in… an instruction manual.

“The very last idea I share in the show is if we could tell each other what is really going on, then people wouldn’t be so frightened. Basically, that’s the message. So, when I look at Hello! I want everybody in it dead. I just want them to die.

“I talk about the nature of envy and how there’s no schadenfreude, there’s just Freud and he’s messed everything up. The worst thing is we lie to ourselves, so I’m saying ‘I’m not going to lie, it would be great if you didn’t either’.

“The stress is that this isn’t a show for mentally ill people or a lecture on depression. I never mention the word depression. It’s about our own foibles and the truth about them without being embarrassed. But it’s not po-faced, it’s fun. It’s the quantum leap from the Vagina Monologues. I’m not using the lower half of my body, I’m using the upper half. I’m using my brain rather than my vagina.”

Any the wiser? Me neither. So what does everyone else think? “There will always be people out there who don’t like what you do. I don’t know who’s coming. How can I?

“But this is serious comedy and like falling in love or dancing, good comedy has a rhythm.”

Ruby Wax’s Losing It is at the Oxford Playhouse on Monday.

For tickets, call the box office on 01865 305305.