Who is Mary (a k a Molly) Waterhouse Flanders Endell Allaun, and what is the mysterious secret of her past?

Mary Waterhouse Flanders Endell Allaun is one of the toughest and most charming heroines to come along in popular fiction in a good while, and the mysterious secret of her past is an irritating buzz in a novel that has no need of such trite devices to keep the reader interested.

Daughter of a poor, working-class family, raised in the slums of London during and after World War II, the cockney Molly "had been bred in the old tradition of women who stand in the street in curlers and slippers grumbling to each other about their demanding husbands and disorderly children as if these chains were all that prevented them from following their true vocations as film stars or the matrons of London teaching hospitals."

Meakin Street is 40 cramped, two-story houses anchored by the Marquis of Zetland pub, where residents gather to backbite and gossip or, when necessary, form a barrier against the outside world. It has bred Sid Waterhouse, bus driver; Tom Totteridge, rag and bone man; Arnie Rose, gang lord; Marge Jones, whore; Lil Messiter, mother of five, worn out, widowed and drunk. If the life of its men is hard, that of its women is harder still.

Molly might work, but not for long: "As with a baby, a husband was expected to be something like religion for a woman -- down Meakin Street the menfolk were discussed as if they were gods, the sort of god which needed a lot of human sacrifice." Molly is too much the daughter of Meakin Street to break that pattern, but she can bend it, letting her dependence be on men who remain outside the system.

Her first husband is hanged for murder when she is 16 and pregnant. Her next lover is a handsome gangster who uses up what money she has and leaves her pregnant and penniless. With a perceptiveness she displays throughout the book, Molly explains her persistent passion for the luckless Johnnie Bridges: "The tragedy is that a lot of rotten men aren't like that in bed. It's when they're on their feet that they get evil or seedy or corrupt. That's what a lot of men don't understand when they see a woman hanging around with a bloke who'd sell his old mother for ninepence and throw his little brother in for free -- they don't know that while they're with a woman for that hour or two at night, they're innocent."

Like her namesake, Molly Flanders, bored and broke, lands on her feet by landing on her back: there is a lord who wants her "passive, always naked . . . if I said dicky bird to him -- he'd hit me," an aging actor and a well-connected pimp right out of the Profumo scandal.

After a liaison with a slumlord whose empire is as shaky as the buildings he rents, Molly finds happiness with a Labour MP, only to learn -- but no, mustn't give away that secret.

Hilary Bailey has set out to create a modern-day Moll Flanders, and like her predecessor, our heroine ends happily -- the respectable Lady Allaun with an empire built on bicycle manufacturing. But the modern Moll with her gritty love of life, her lack of illusions about herself or the world around her and her self-mocking humor is nicer than Defoe's.

She is happily at home in the vivid world of working-class London, and the book's most memorable characters are those at the bottom of the social scale: the pimp who encourages Molly to read because, with "no inner life, no nothing . . . you'll be a pain in the neck to yourself and everybody else," the homosexual who runs the gambling club where Molly works, the Rose brothers, gangsters whose cruelty does not extend to Molly because "my mum was at Wattenblath Road School with both of them."

Presumably, it was the need to keep the modern Moll on a parallel course with her predecessor that led the author to push her most reluctant heroine into the upper classes and to create for her an improbable past. It does not spoil an otherwise energetic and bawdy book, but it remains a strand that does not blend.