She is always cautious during interviews, staying well clear of the personal.
But today, as well as talking about her role in the RSNO's Christmas show, The Snowman, the former member of the Royal Shakespeare Company tells an incredible story.
In 2000, Maureen, daughter of comedian Johnny Beattie, was standing in the wings of Glasgow's Old Fruitmarket to star in Medea, one of the most demanding classic theatre roles.
However, despite winning a clutch of acting awards over the years, including Best Actress at the RSAMD where she studied, Maureen was petrified.
"We were in the Fruitmarket, for the first time, and I was standing behind the curtain," she recalls in a coffee shop in London's Clapham Junction, close to where she lives.
"The build up was incredible and I was terrified.
"Suddenly, I remembered my mother, who had died eight years earlier, was responsible for this performance space. She'd gone to the council and battled to have it put in place.
"Anyway, I just didn't know how I'd make it on to the stage. So I had a word with my mum. I asked her to come down from a great height, put the gin and tonic down and give me a hand."
And that's what happened.
She said: "All of a sudden I felt her hand on my back pushing me through the curtain. She shoved me right on to the stage. And from that point I walked out there and felt I could do exactly what I liked."
What makes the story rather more poignant is that Maureen, a former Notre Dame pupil, had long since given up on religion.
But it's also something of a revelation given she rarely speaks of family, of siblings Mark, Paul and Louise (of Emmerdale fame, now with the procurator fiscal's office) or indeed her mum, the former model-turned showbiz agency boss, Kitty Lamont. Mark could have been a comedian, she believes – he works for the DSS.
But Maureen, whose first bed was a drawer in her parents' digs in Ireland where her dad was appearing, was on stage almost as soon as she could walk, singing Mairi's Wedding.
WAS it an odd upbringing? "I didn't know what 'normal' was," she admits.
"Dad toured, and then this exciting person came home, or we'd rent the flat out and go out to the seaside for the summer season.
"My mother wasn't a Katie Oxo, cuddly-bunny, roaring-fire mum. She needed little sleep, could bake and ran a successful agency. She was always positive."
Beattie was a slightly out-of-sorts teenager who would learn Shakespeare speeches 'just for the love of it'.
She was the last to wear make-up, the last in her group to have a boyfriend. And she reveals now her weight was also an issue in her life.
"Yes, it made me miserable. My body image was bad but I wouldn't want to yabber on about poor me because lots of young women suffer from it."
Set to leave school the acting dream was alive and well, but the concerned young girl determined she'd first save the starving as a volunteer.
Fate intervened with a job offer in Perth as a comedian's feed. With it came a coveted Equity Card.
"I think my parents offered Larry Marshall 15 quid a week to take me on," she says, with a grin. "I really must tackle dad about that."
Is she one of the many actors who love to inhabit characters because they are not entirely happy in their own skin?
"I'd like to think it's not true of me," she says, smiling. "But then you have to say 'When do you stop acting?'
"I was aware from an early age of being recognised, not just being myself but being rep-resentative of a 'dynasty', which is Johnny Beattie and Kitty Lamont's daughter."
So she could be performing now? "Of course I am." When is she not performing? "When I'm asleep," she says laughing.
"I remember playing a part in a play in which a couple were splitting up. And at the time I had a huge argument with my then boyfriend, and I found myself quoting from the play. Or at least he realised I was."
Maureen, now single and happy to be so, says she's like most actors, she 'wants to be the best thing in a brilliant show'.
"I believe my early days of watching the likes of Anne Fields take the stage in a village hall has had an enormous impact. It's given me a third eye, to see what I'm doing."
Outside of acting she likes to ice cakes – she shows some incredible photos – does lashings of charity work and has a house on Bute. But work is the main focus, such as the chance to narrate The Snowman.
"What's not to like?" she says of the show. "It's just fantastic to join in the Christmas razzamataz."
l The RSNO's The Snowman, Glasgow Royal Concert Hall, December 22 at 2pm and 6pm.