Shani was born at Deen street in the Tottenham High Road. North London. Her parents (Jim and Ethel) owned a Delicatessen, and use to supply a lot of the restaurants and hotels in this area. In 1937 she made her first stage appearance. When in1940 when the bombing got bad in London, her father brought her and her two brothers, Jimmy and Leon, to Wymington and stayed there until the end of the war. Shani attended the village school and won a scholarship to The Wellingborough High School. The family later returned to London where Shani initially studied at the Royal Academy of Dramatic Art on a scholarship. 
A few inconsequential film roles had come her way earlier in England, including The Extra Day (1956) and Ramsbottom Rides Again (1956), not to mention a minor singing bit in Charles Chaplin's A King in New York (1957). Other than assorted variety show appearances and a televised performance supporting Carol Burnett in Once Upon a Mattress (1964), she found only a modicum of on-camera work. All the more astounding then when she nabbed the role of a lifetime as the ill-fated Nancy in the Oscar-winning picture Oliver! (1968). Successfully replacing the seemingly irreplaceable Georgia Brown, Shani made a durable marquee name for herself while giving her all in the rousing "Oom-pah Pah" number and putting her own indelible stamp on the show-stopping "As Long As He Needs Me," now considered her signature song. Having never played the part before, she went on to perform Nancy on the theatre stage as well.
In addition to her participation in the soundtrack album from the movie "Oliver!", her recording career included several singles (released on 78 and 45 RPM) on the Philips label in England in the 1950s and 1960s, and one single released in the USA on London Records in 1963. Also, several LP records on the Kapp label in the USA in the 1960s.
Shani was seen only sporadically in films following this breakthrough for the live stage was still her first love. Over the years she has gamely performed in a number of musical staples, including "42nd Street" and "Follies," and toured with Liberace for five years during the 1980s.
Shani has also appeared in TV series such as Charlie’s Angels and Murder She Wrote, was a regular in daytime soap The Young And The Restless, and popped up in films like Terror In The Wax Museum and The Mojave Phone Booth. In September 1992 Shani came back to Bath, England for 5 weeks to appear in a play.Since losing her husband of 48 years, actor Bernie Rich to cancer in 2016, Wallis has moved to a condo in southern California where she keeps mementoes of her career. Their daughter Rebecca, who works in pharmaceuticals, and grandchildren also live in California. Shani still keeps herself fit, proud to still be a Size Zero, and continues to sing and play piano and is working on her autobiography “It’s A Fine Life.”
Shani's brother Leon had a record shop in Rushden but later died at Souldrop, U.K.. Her other brother Jimmy emigrated to Australia. He had eight daughters all of whom followed in their aunts footsteps and become actresses in various soaps.
(Edited from various sources mainly a bio by Gary Brumburgh for IMDB)