The English countryside was pillowed in darkness, but actor Peter Sellers was pacing about his manor house, too excited to consider sleep. Once again he was in the grip of a burning passion, the latest of the frantic romances that flared and flickered throughout his troubled life. This time the mercurial actor had deluded himself into thinking that his current co-star, Sophia Loren, was in love with him and about to ditch her producer husband, Carlo Ponti. At 3 a.m. Sellers shook his 7-year-old son, Michael, awake. As the boy rubbed the sleep out of his eyes, his father asked him an extraordinary question: “Do you think I should divorce your mummy?”

The suggestion left the boy bewildered, frightened and sobbing, and, as Michael Sellers, now a 27-year-old London carpenter, recalls, the incident was nothing unusual. In his new book P.S. I Love You, written with his sister, Sarah, and half sister, Victoria, Michael maintains that being there with Peter Sellers was no comedy. The book—to be published here by E.P. Dutton ($12.95) in March—depicts the comic genius as a private monster, an insanely jealous, wife-beating husband and a hopeless father. “He was a child who never grew up,” Michael recalls. “I used to be scared stiff of him.”

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Peter Sellers’ volatility was never a secret. The infatuation with Loren fizzled, but he fell wildly in love time after time. Before his death of a heart attack in 1980 at age 54, Sellers logged four unsuccessful marriages, a broken engagement to Liza Minnelli and scores of other unhappy endings. He rattled from one religion to the next, dabbling in both Roman Catholicism and Eastern mysticism, changed houses with dizzying frequency and bought and discarded more than 200 automobiles. As Michael tells it, secretaries and household pets suffered peremptory dismissal and banishment as soon as they fell from grace. One terrified nanny leaped from her bedroom window as the enraged Sellers embedded a carving knife in the door. Preoccupied with the search for a happiness that always eluded him, Sellers inflicted his manic whims and moods on the children, switching them unpredictably from one school to another. Michael, who attended nine different schools, was once diagnosed by a psychologist as “an insecure child lacking the attention of his father.”

For all their revelations, the Sellers children are more sympathetic toward their father than vengeful. Near the end of his life his father was suicidal and terribly lonely, Michael recalls. “I saw the desperation that imprisoned him,” he says. The children save much of their vituperation for Lynne Frederick, the 27-year-old actress who was their father’s last wife—and the main beneficiary of his multimillion-dollar estate. Sellers had disinherited his children some time earlier, thinking them unworthy and ungrateful. Michael claims that Lynne and Sellers had come close to divorce, and adds that only six months after his death she married her old flame, David Frost. “I think it’s obvious she’s a good actress,” snaps Sarah, now 24 and part owner of Being There, a London antique-dress shop. “I’ve never seen anything like her performance when Dad died. She was hysterical, screaming and crying her eyes out.” Yet Frederick was not so distraught, according to the book, that she could not spend part of the afternoon after her husband died on the phone in her hotel suite discussing the purchase of a new Porsche. “Most of the references to me in the book are inaccurate,” Frederick maintains. “It was I who persuaded Peter in the last year of his life to see Michael.”

Victoria, 17, daughter of Sellers’ second wife, Britt Ekland, is planning an acting career. She lives with her mother in Los Angeles, and has refused to comment on the book. Sarah and Michael, the offspring of his first marriage, to actress Anne Howe, are voluble. “My mum tells me I turned out well, considering,” says Michael, flashing the toothy Sellers grin. “She was surprised.” His father wanted him to be a film director and scorned his work as a carpenter. “But,” says Michael, “I find it very satisfying-working with my hands, building things.” After an unstable childhood and flirtations with drugs and petty theft, Michael showed signs of settling down in 1979, when he married Carolyn Athay. His father’s wedding present was a $5,000 leather sofa set. His wife left him after six weeks, but Michael still has the furniture, which dominates the four-room apartment he now shares with his 27-year-old American girlfriend, Alison Park. In spite of the disinheritance, Michael may soon recover some of the affluence he knew as a child; the book has already earned $170,000 through serialization in Britain. Michael’s share, presumably, will help him sustain the Sellers passion for extravagant cars. He is surely the only carpenter in London who carries his lumber on the roof of a 17-foot Lincoln Continental.

Sarah has used her share of the book money to buy a one-bedroom apartment not far from Michael’s. She likes to cook and entertain at home, and seems utterly without nostalgia for her father’s more opulent life-style. “When I was little, I liked being Peter Sellers’ daughter and I was a terrible show-off,” she admits. “When I was about 11 I realized it wasn’t a good idea. It wasn’t getting me anywhere.” Sellers’ mood shifts were capricious and frequent, and Sarah struggled vainly to find a stable relationship with him. “I couldn’t always understand why he behaved as he did,” she says simply. “I wanted to know him better.”