Going back seven months earlier to July 1961, life is still more or less the same for the Trotter family. Del continues to pursue countless girls with his glass rings, Reg is still unemployed, and Joan works for Freddie "The Frog" Robdal as his "charlady", although they really use their time together for sexual pleasure (unknown to the rest of the Trotters, Robdal is the father of Rodney). Robdal, for his part, keeps his own eyes on the Trotter family, going as far as to assault Joan's lecherous employer, Mr. Raynor, by breaking his fingers and threatening him into silence after learning of his perverted behaviour towards her through gossip in the Nag's Head.
Del crosses paths with an old flame of his, Barbara Bird, and they go for a coffee together, where they agree to continue seeing each other but only after Barbara returns from an upcoming trip. Around the same time, Robdal gives Joan a ring as a gift, which she notices is from Margate. She asks Robdal if he stole this ring from the jewellery store in Margate while on the 1960 Jolly Boys' Outing with Del, but he denies it. Robdal and his friend, Gerald "Jelly" Kelly, are approached once again by the corrupt DI Thomas and DC Stanton, who now claim to have a one-eyed war hero eyewitness, Eric Poulton, to the Margate robbery, and later on, Thomas arrests them both when Poulton goes missing. However, Robdal comes triumphant once again when it is revealed that Poulton is actually a policeman who lost his eye in a street fight and served as the desk sergeant when DI Thomas first started as a policeman. It turns out Poulton was living in Margate opposite the jewellers, and Thomas asked him to tell a few "white lies" in return for a share of the reward money, but Robdal and Kelly paid him a visit and told him their side of the story, treating him to a holiday in Spain. All but defeated, Thomas begrudgingly drops the case, but once Kelly is gone, Thomas plays his trump card: he has acquired the ring which Robdal gave to Joan, which she recently pawned in order to buy Del a lambretta. Despite furiously threatening Joan over the phone, Robdal chooses to protect Joan and Del (and get Thomas off his back once and for all). Robdal subsequently takes the full blame and is imprisoned on an alternate charge for a few months while Kelly goes free.
Del, meanwhile, begins his own plans to make a film, "Dracula on the Moon", and become a millionaire. Joan, under the name "Reenie Turpin" (Trigger's aunt and Joan's best friend), visits Robdal in prison. Robdal claims that once he is released, he wants to move to his country house near Bournemouth and start a new life, and implores Joan to run away with Rodney to live with him (although this would be an act of kidnapping). Joan accepts, but tells Robdal that she will only leave with him once she is certain of Del's financial security, even though Robdal, knowing of Del's life as a market trader, believes Del is old and smart enough to look after himself. During the conversation, Joan mentions that she briefly began working as a charlady for an art dealer, Roland Pernell, for seven pounds a week, although Pernell callously deducted three pounds from her salary for "tax reasons". This, as well as the mention of Pernell's name, pique Robdal's interest.
To get Del set up financially, she pushes his relationship with Barbara, who comes from a rich family. Del takes Barbara out to dinner, where he gets engaged with her. Barbara's parents, Bernard and Beryl, take a liking to Del and invite his family over for an engagement party, during which Reg gets drunk and makes a fool of himself. Unfortunately, whilst alone in the kitchen, Beryl makes a sexual pass at a surprised Del and is seen by the rest of the family. Beryl confesses that she never had the happy, privileged life Barbara had, and became so jealous, especially with her disturbed childhood and unhappy marriage to Bernard, that she began secretly dressing in Barbara's clothes and listening to her music while alone. Despite Joan's efforts to patch things up, the engagement is off, and Joan ultimately decides to remain in Peckham for Del's sake. Meanwhile, Robdal and Kelly rob Pernell's art gallery together: many years back, Pernell cheated Robdal out of some money and went into hiding. Once Robdal went to jail, Pernell re-emerged, opened a new art gallery, and cheated Joan out of almost half of her wages. By robbing Pernell, Robdal will make him a target for the Inland Revenue for tax fraud. Following this, Robdal vows to go straight, unaware of Del's failed relationship.
Returning to the opening scene, while Del and his friends share a smoke outside, Joan reads Rodney a bedtime story and laments how both her and Del's happy futures were ruined. The door slams and Reg comes inside, surprisingly calm and expressing relief that Del's relationship with Barbara is over, having been disturbed by Beryl's actions. Reg goes to bed, leaving Joan to sit with Rodney and wait for Robdal to call (unaware that he himself is waiting for Joan to call him). Del and his friends, meanwhile, steal some lambrettas and ride off into the night towards Brighton asWill You Love Me Tomorrow by The Shirelles plays in the background to mark the definitive end of the series.