Mary arrives in Walford in March 1985 when she is housed in Reg Cox's (Johnnie Clayton) old council flat (23b Albert Square), following his death, bringing her daughter, Annie Smith.

Strapped for cash, Mary finds it difficult to provide for Annie, so her friend Sheena Mennell (Dulice Liecier) talks her into becoming a stripper and she regularly dances for married shopkeeper Saeed Jeffery (Andrew Johnson).

By December 1986, Mary is persuaded to turn to prostitution by Pat Wicks (Pam St Clement), who is being pimped by Mehmet.

She starts making regular trips to Central London and comes home late one night covered in bruises and blood.

Despite this, Mary refuses to stop prostituting herself, even when the healthcare worker, Carmel Roberts (Judith Jacob), warns her that her baby might be taken away from her if she continues.

Mary's unsocial hours mean that she is often forced to leave baby Annie alone at night whilst she goes out to work the streets.

In 1987, Mary begins a relationship with Rod Norman (Christopher McHallem); a good-hearted, scruffy, layabout who has a soft-spot for women in distress.

Mary is frequently frustrated by the amount of time it is taking for Social Services to decide who should have custody of Annie, but Rod keeps her going and even manages to get her a job as cleaner in The Dagmar winebar.

She refuses, but on Christmas Eve, after getting extremely drunk, Chris snatches baby Annie and attempts to drive her back to Stockport with him, only to crash his car into a garden wall before he can leave.

Mary begins to behave erratically again, regularly taking drugs and begging around the Square for money to fund her habit.

She becomes an unwitting pawn in Simon Wicks's (Nick Berry) game to bed as many women as possible and is later hurt when he cruelly rejects her.

However, upon the arrival of her mother, Edie, Mary decides she is sick of her family's interference, and after vandalising her father's business with paint, she takes Annie, jumps on a bus and leaves Walford, sticking up two fingers in the air as she goes.

Over thirty years later, Mary and Annie (now played by Marilyn O'Brien) return for the funeral of Doctor Legg (Leonard Fenton), where they reunite with old friends, Dot, Lofty Holloway (Tom Watt), Sharon Mitchell (Letitia Dean), and Kathy Beale (Gillian Taylforth).

Mary's original character outline as written by Smith and Holland appeared in an abridged form in their book, EastEnders: The Inside Story.

[1] However, actress Jenna Russell revealed in 2016 that the part was originally offered to her, saying, "I was asked to play Mary Smith in the show right in the beginning when it started in 1985, but I was very young and it wasn't the right fit for me then".

[2] Mary was one of the most striking of the original characters: a lone mother with a small baby, who hid herself under punk makeup, was unable to read or write and was a northerner alone in a southern city.

[1] The character of Mary lasted in the show for three years, and was eventually written out of the series when Linda Davidson decided to leave in order pursue other acting roles.

[4] Executive consultant John Yorke invited Davidson to reprise the role and described Mary as a "huge iconic characters, and a central part of the show's DNA".