“I can drink anyone under the table,” she boasts, “and I’m the last person on the dance floor. I’ll give you all your own start but three o’clock in the morning and I’m still there, I’m still giving it, I love it.
“To be honest, I’ve got so much alcohol in my system it don’t even register in my body anymore. I don’t get hangovers, nothing. I think it’s what keeps me young. I’ve got a pint of Guinness in my hand before 11 o’clock in the morning, that’s the trick.”
She looks down at the bottle in her hand.
“But I’m hydrating today. It’s just water. A rare moment. I didn’t know it tasted like that, to be honest.”
Tate’s character of Joannie Taylor, also known as Nan, originated in her sketch comedy series The Catherine Tate Show in the late 2000s and became so popular she got her own spin-off on BBC One. Now she’s heading for the big screen in her own film, aptly titled The Nan Movie, and more outrageous than ever.
Sitting opposite her in character is slightly surreal, like she has walked straight off the TV and into this fancy suite, but Nan is warming to her theme and feeling slightly miffed it took years for her to get her cinematic dues.
“I think the big question is, why did it take so long? I mean clearly I belong on a silver screen, and I’m very, very grateful that it finally materialised.
“It’s ageism in reverse, they are falling over themselves to employ me now. You know I’ve had the call, don’t you?,” she confides with a sly wink.
“You know they want to give me my superhero movie? Batnan. It’s coming.”
Sounds a like a surefire crowd pleaser. Would she be doing her own stunts? “Very much so. My superpower is I can dance without peeing myself.”
So no flying? “Oh I want all that too,” she adds hastily. “Hoist me up in a harness. I love doing that.
“In this film I do that thing where you skydive on people … body dive? What’s it called? Crowd surf! Oh, I loved that. They put a big camera on me and I went back, I had lots of goes, I’m game for anything.”
Nan’s crowd-surfing episode might have been the result of a few too many jagerbombs (when a shot of Jagermeister is dropped into an energy drink, typically Red Bull) while on a road trip with her grandson (Gavin and Stacey’s Mathew Horne reprises his role from the TV show).
“I’m very au fait with all the drinks, I’m very au fait with cocktail hours,” she says, but she also loves the company of energetic young people. Her verdict on millennials? “I love them all. You can learn from every generation, every generation learns from the other, you’ve got to open it up to discussion.
“Don’t shut the door, don’t shut the door on the old people. And don’t shut the door on the young. The middle aged ones can go f*** themselves,” she adds with a cackle.
What about Gen Z and TikTokkers? “I love it, TikTok. I’m going to TikTok soon, I’ve got a dance prepared,” she says.
With that she burst into song, crooning the viral track Classic by MKTO – “‘I’ma pick you up in a cadillac, like a gentleman bringing glamour back’. I can do the dance. I’ve studied it. That’s coming out soon on Tick Tack. Tick Tack Toe? TikTok?
Even though she’s advanced in years – “I think if you work out the age, I’m actually 104” – she is still feeling agile.
“Yes darling, I do my exercises. I can’t remember what they are called, 99s or something, to keep the hip joints mobile. My hips are my own.”
And she’s also adamant she is young in heart and mind. “It’s all up there,” she says, tapping her head. “Keep yourself young, be across pop culture. You’ve got to be interested in all ideas, have opinions. Don’t be afraid, let’s have a laugh.”
With so much energy to spare, she’s got her eye on dominating both the big and small screen in her dotage.
“I’ve got a couple of sequels lined up, they are in the bag. I’ve got Batnan. I’m going to do a version of Judge Judy called Judge Nan and will bring people in my living room and say ‘My decision is final, now get out of my sitting room’.”
Will she be a tough judge? “It depends. I’m very open and I can also turn on a penny so if I don’t like the look of someone that will be it.”
In the meantime there is her rigorous training schedule for the definitely-not-real Batnan film.
“I’ve got my Malibu Pilates table. I got that during lockdown, got a load of other old toot off the internet that I don’t want too. I’ve got protein shakes coming out of my ears, it’s probably why I can do so much.
“I’ve got a personal trainer, personal chef, a driver. That was just me chancing my arm,” she says with a wink, “I’m not going anywhere, he just sits outside my block of flats.”
And with that she descends into more uproarious cackles.
The Nan Movie is released in UK cinemas on March 18.