BARELY have I plonked myself down into a chair next to Arabella Weir, than we're off and running.

Most interviewees need time to warm up, but I'm still fishing out a notebook when – above the hubbub of noise in an upmarket Glasgow hair salon – she launches into a story about her "horrible Dunfermline granny" that had "something negative to say about everyone in the world".

If there had been a seatbelt, I would have buckled it at this point. Over the next hour, the comedian and writer – who coined the catchphrase "Does My Bum Look Big In This?" for hit BBC sketch series The Fast Show – fires off a volley of witty one-liners alongside colourful anecdotes about her life.

There are moments where it feels like I'm staring into her soul. "My mother and I always had a tricky relationship," Arabella tells me at one stage. "I was very fond of her, but she was by no stretch of the imagination 'a mother'. She was aggressive and withering."

She equally reflects on how the first seeds of negative body image took root at a formative age, portraying a child who felt like a constant source of disappointment to her parents.

"They never stopped going on about how fat I was from when I was little. I think my parents were embarrassed that I was short and plump. I look at pictures now and think: 'Christ, I'm nothing like as fat as they made me feel.' I thought I was enormous."

With such unflinching honesty, it is easy to get side-tracked from the task at hand: talking about her role in BBC Scotland sitcom Two Doors Down.

The show returns for a second six-part series on Monday with Arabella playing Beth Baird, the ballast of neighbourly relations in fictional Latimer Crescent.

When we meet, the 58-year-old actor has newly wrapped filming and cheerily describes being reunited with cast-mates Elaine C Smith, Jonathan Watson, Alex Norton, Sharon Rooney and Doon Mackichan as "a bit like a second date, but not quite as terrifying".

The dynamic is reminiscent of her time working on The Fast Show in the mid-1990s. Charlie Higson, she says, would describe himself and co-creator Paul Whitehouse as the mum and dad of "one big f***** up family". To which Arabella would quip: "but just as f***** up as the kids".

Two Doors Down has a similar happy yet dysfunctional family vibe among its cast. "But in our group, there is no one clear mum and dad," she clarifies. "We are either all bickering children – or we are all the parents – depending on the mood."

The latest series was filmed at BBC Scotland's studios in Dumbarton and on location around Glasgow. "They are a lot more scenes with us all together," she says. "I think they thought quite rightly that those are the ones that work best.

“If you take Till Death Do Us Part, Porridge, any of the great sitcoms – it is when everyone is in the room that it is the most fun to watch."

Arabella, born in San Francisco to Scottish parents, was particularly fond of working alongside Elaine, best known for playing long suffering Mary Doll in Rab C Nesbitt, and Doon, who previously starred in Channel 4's Smack The Pony.

"There is some very good comedy stuff with Elaine and Doon's characters driving it," she says. "Elaine is a much bigger presence [in this series] than she was before.

“That is probably because her character is the best vessel for the greatest jokes that are so awful that no one else can say them.

"She has got a number of fantastic gags. I always think of Elaine's character as slightly the Mrs Slocombe [from Are You Being Served?], this extreme character who can say the things an ordinary person can't. If Beth made half her jokes, you would think that she had gone completely mad …"

The lack of older women gracing our television screens is an enduring thorny issue. Only last month Ofcom chief executive Sharon White said that the BBC is "falling short" on its obligations in this area.

In that context, Two Doors Down is arguably a welcome breath of fresh air. "It was Elaine who pointed it out: how often so you get three women over 50 in a show?" says Arabella.

The opening episode of the new series sees the long-suffering Beth railroaded into hosting a barbecue, stoking the flames for some hilarious scheming shenanigans as her neighbours gather to indulge in their favourite pastime: one-upmanship.

Arabella, known for her TV roles in Skins, Doctor Who and Drifters, lives in north London "along with all the other Scottish actors". She gives a wry smile. "There is quite a lot of us in our square mile: Peter Capaldi, James McAvoy, Sylvester McCoy and until recently David Tennant ...”

I'm curious how Arabella's real-life neighbourly relations compare to that of her on-screen alter ego. "I'm very fortunate in that I'm good, close friends with at least eight of my neighbours," she says. "That is very unusual in London and probably most urban areas.”

She describes herself as "an extremely good but also a little bit of a nosy neighbour." Define nosy, Arabella? "I might be fully aware of what everyone does. Although not quite a curtain twitcher, I am part of the local Neighbourhood Watch."

As it transpires, Arabella even has a nickname. "My very good friend – who is also my neighbour – says I'm the 'Neighbourhood Witch', which is a play on 'Neighbourhood Watch'. She bought me a sign for my window that says: 'The Neighbourhood Witch lives here.'

“Beth in Two Doors Down is more benign. She would go: ‘Feel free to park your HGV right in front of my house’, whereas I would be straight onto the police saying: ‘No HGVs allowed in this area!’”

Two Doors Down begins on BBC Two, 10pm, on Monday. Thanks to Taylor Ferguson (taylorferguson.com) and Abode Glasgow (abodeglasgow.co.uk)