Yet, as the Manchester-born actress arrives in Aberdeen this week to play the latter in Jo Clifford's stage adaptation of Charles Dickens's Great Expectations, those characters are bookends of a sort on a career that has seen Wilcox move from 1970s TV sitcom star and household name to classical stage actress with ease.
Not that the still-youthful-looking 62-year-old's career is over yet. Far from it, in fact, if recent stage turns in everything from a musical role in La Cage Aux Folles and playing an ageing rock chick in Stella Feehily's play, Dreams of Violence, for Max Stafford Clark's Out of Joint Company, to a new play by Jonathan Harvey at Liverpool Playhouse, are anything to go by.
It's just that, there's something about the hopelessly romantic Beryl in Jack Rosenthal's sitcom The Lovers, in which Wilcox led Richard Beckinsale's Geoffrey on a merry dance for two series in 1970, that could have easily ended up as bitter and twisted as Miss Haversham.
"She's had a rather terrible life," Wilcox says of Miss Havisham in the call-a-spade-a-spade northern English accent she's retained over her 42-year career.
"She got jilted at the alter and has never forgiven man as a gender, and has been wreaking her revenge ever since. She's a real mixed-up contrary bag of tricks, and what I find phenomenal about her is that it's not just a great anger, but a great sadness that's made her such an evil person.
"Part of her problem is that she's so incredibly wealthy. So, unlike most people who have to get a job, which might help them get over things, she's never had to, so she's had all this time to indulge her mad desires in this really self-indulgent fashion. This results in the tragedy of what's happened to them all. As [Miss Haversham's adopted daughter] Estella says, they're all beaten and broken."
Great Expectations was Dickens's thirteenth novel, and tells the coming-of-age tale of orphaned Pip, who makes his way through society care of a secret benefactor he presumes to be Miss Havisham, even as she makes his and Estella's life a misery.
Graham McLaren's touring production of Clifford's adaptation originated in a smaller version at Perth Theatre itself. The script itself dates back to 1988, when Clifford wrote it for Glasgow-based theatre in education company TAG. That production featured eight actors, dancers and musicians, including a young Alan Cumming playing Pip.
Ian Brown's production went on extensive tours of India and the Middle East, something unheard of for small-scale Scottish theatre companies at the time.
The current tour of Great Expectations comes at a time when there is an ongoing flurry of interest in Dickens's work.
A three-part TV serial in 2011 featured Gillian Anderson as Miss Havisham, while a new feature film adaptation by Four Weddings and A Funeral director Mike Newell will star Helena Bonham Carter in a film that also features Robbie Coltrane and Ewan Bremner. McLaren's production, now scaled up for a cast of 15, is an infinitely more theatrical proposition.
"The script is very clear," says Wilcox. "Jo's jettisoned a lot of characters and sub-plots, and focuses on the main story, from when Pip meets Estella and dreams of becoming a gentleman. Whenever I say to anybody I'm doing Dickens on tour, that doesn't sound too exciting, to be frank, but the way it's done, as a memory play, with all these stage effects and music and lighting, that's much more attractive and terribly exciting to do."
Wilcox's career began as a teenager while attending The Hollies FCJ school, Manchester's oldest grammar school. In between entertaining her classmates with impressions of the school's famed headmistress, Sister M Victorie Murphy, young Mary Paula Wilcox found herself captivated by a school trip to see Shakespeare's Henry IV Part One.
Wilcox applied to join the National Youth Theatre aged fifteen, but was turned down, only being accepted on her second attempt two years later. It was here Wilcox was spotted by Jack Rosenthal and producers from Granada TV, who were looking to cast the lead in a new sit-com. By the time she was eighteen, Wilcox had been given the lead role in The Lovers.
Rosenthal's writing captured the conflicting social mores of the period perfectly, with Wilcox's prim suburban Beryl sparring beautifully with Richard Beckinsale's football daft and perennially randy Geoffrey, for whom the promise of the permissive society remained frustratingly elusive.
Running to two series, each episode of The Lovers was a little kitchen-sink playlet recorded in just one or two takes before a live audience. The success of The Lovers launched both actors careers, with Wilcox going on to even greater sitcom success in flat-sharing romp Man About The House with Richard O'Sullivan and Sally Thomsett.
Both programmes were so successful they were made into feature films, and made everyone involved household names.
"I think I was a bit embarrassed by all that," Wilcox reflects. "I wasn't really that comfortable with being recognised all the time."
After leading one more sitcom – the single mum-based Miss Jones and Son – Wilcox took advantage of the doors her success had opened, and concentrated on theatre.
This doesn't mean Wilcox has been completely absent from the small screen, with Wilcox a series regular in latter-day sitcom The Smoking Room as well as doing a stint in Emmerdale in between theatre shows.
"I've just gone with my heart," Wilcox says. "And what I've found as I've got older is I'm getting to play lots of weird and wonderful characters."
Miss Havisham is a prime example of someone who could learn much from Wilcox's openness to new experiences.
"I think she's learnt what a tragic disaster she's made of her life and Estella's life," Wilcox observes, "and she's learnt that, if she had her life over again, she'd live it very differently."
Great Expectations, His Majesty's Theatre, Aberdeen, November 6-10 www.aberdeenboxoffice.com