She was born Sheila O'Nions in in Birmingham, England, UK. During the Second World War, her family moved to Southport, Lancashire, where she met Des Walsh, son of Thomas Walsh, who had a jewelry store at 39 Chapel Street since 1926. In 1950, Sheila married Des Walsh, and they had two daughters, Fran Walsh and Tess Walsh. Sheila worked during years in her husband's familiar jewelry store, with her husband, her husband elder brother Gerard and his wife Dorothy.

In 1971, Sheila joined the Southport Writers' Circle, and years later, in 1986 was elected life president. In 1980 she became the vice-president of the Romantic Novelists' Association, and later elected Chairman (1985—1987)

Her debut novel, The Golden Songbird, won the Netta Muskett award for new writers from the Romantic Novelists' Association, and in 1984, her novel, A Highly Respectable Marriage won the Elizabeth Goudge award.

Sheila Walsh died at age 80.

As Sheila Walsh

Single novels

• The Golden Songbird (1975)
• Madalena (1976)
• The Sergeant Major's Daughter (1977)
• Lord Gilmore's Bride = A Fine Silk Purse (1978)
• The Incomparable Miss Brady (1980)
• The Rose Domino (1981)
• A Highly Respectable Marriage (1982)
• The Runaway Bride (1983)
• The Diamond Waterfall = Cousins of a Kind (1984)
• The Incorrigible Rake = Improper Acquaintances (1984)
• The Wary Widow (1985)
• An Insubstantial Pageant (1986)
• Bath Intrigue (1986)
• Lady Aurelia's Bequest (1987)
• Minerva's Marquis = Minerva's Marquess (1988)
• The Notorious Nabob = The Nabob (1989)
• The Arrogant Lord Alistair (1990)
• A Woman of Little Importance (1991)
• Until Tomorrow (1993)
• Remember Me (1994)
• The Perfect Bride = Cornwell Bride (1994)
• Kate and the Marquess (1997)
• The Lady from Lisbon (2001)

Omnibus

• "The Christmas Star" in A Regency Christmas (1989) (with Mary Balogh, Sandra Heath, Emily Hendrickson, Emma Lange)
• A Regency Christmas II (1990) (with Mary Balogh, Carla Kelly, Anita Mills, Mary Jo Putney)
• "Midsummer Masquerade" in A Regency Summer (1992) (with Mary Balogh, Charlotte Louise Dolan, Sandra Heath, Melinda McRae)
• "Dear Delight" in Tokens of Love I (1994) (with Mary Balogh, Sandra Heath, Carol Proctor and Margaret Westhaven)
• "It Came Upon a Midnight Clear" in A Regency Christmas VI (1994) (with Mary Balogh, Sandra Heath, Emily Hendrickson, Emma Lange)

As Sophie Leyton

Single novels

• Lady Cecily's Dilemma (1980) aka The Pink Parasol (as Sheila Walsh)