Shirley is initially seen in Albert Square in May 2003. A divorcée, she has three sons, now grown up; two are in the army and the other lives in New Zealand. She works at the Turf Accountants and lives with her cat, Boots, at 89A George Street .
Dan Ferreira needs a date for an upcoming wedding, so he asks Shirley and she agrees. Dan tells Shirley that his wife, Pushpa Ferreira, is dead, when they have only separated, following Pushpa's infidelity. At the wedding, everyone is enjoying the day until Pushpa introduces herself to Shirley. She is mortified to discover Dan's lies, telling him that her ex-husband was a liar and she is not prepared to put up with lying again. She also tells Dan that she wants nothing more to do with him.
In August that year, Shirley has problems with her new neighbour, Gavin Sharp. He lives in the flat above hers and plays extremely loud music at all hours, meaning Shirley cannot sleep. She tries reasoning with him several times but he laughs at her, only playing his music louder, so she complains to the council. Maddened, Gavin threatens to make her life a misery as payback. Days later, Shirley's cat disappears and Shirley fears that Gavin is responsible. Whilst Dan confronts Gavin about Boots, Little Mo walks in to The Queen Victoria pub, cuddling Boots. Shirley rewards her with money but later that day, Shirley finds Boots on her doorstep — dead in a plastic bin bag. Shirley turns to the Ferreiras for help, and Dan confronts Gavin again. Gavin denies killing Boots and says that he found her lying dead in the road and left her on Shirley's doorstep so she could bury her. Shirley, however, is not convinced. Gavin's taunting continues when he puts her telephone number on a card, advertising her as a prostitute, and distributes it across Walford. Later, while she is at work, Gavin breaks into her flat and tips rotten rubbish all over the floor. Shirley is distraught, and seeing her angst, Ash Ferreira, decides to help. He plays Gavin at his own game, borrowing his brother's amplifier and speakers and playing dance music extremely loudly. He then breaks into Gavin's flat and lets a rat loose. Gavin is petrified of rats and when he discovers it, he agrees to call a truce if they remove it.
The saga brings Ash and Shirley closer together and it is not long before they start a relationship. Ash wants to keep it a secret because he knows his father will be furious if he finds out. Shirley begins to get irritated with Ash's inability to tell Dan, particularly when Dan tries to woo Shirley for a second time. Ash explains that he had been a compulsive gambler, and Dan had bailed him out of serious financial difficulties after he lost his house and his wife. He owes his father everything and is unwilling to hurt him. However, when Dan tries kissing Shirley she told him that she is with his son, Ash. This revelation causes huge rows at the Ferreiras' and although Ash loves Shirley, he feels he has no choice but to finish with her to keep the peace.
In February 2004, Andy Hunter takes over the bookies where Shirley works. Shirley does not like the way Andy runs things and after she complains repeatedly about his conduct, Andy fires her. Shirley demonstrates about her unfair dismissal with a placard outside the bookies. Eventually Andy offers her a large sum of money to leave. Shirley is thrilled with the pay-off and decides to go to New Zealand to visit her son.