The theatre benefited from a capacity of 1,426 on three levels and a stage that was wide, with a depth of . The interior was opulent, The Stage reviewed the new theatre on its opening
The stalls bar and saloon lounge adjoining, will please the public, special care has been exercised in their equipment and decoration. The bar, which has mural paintings by Mr A. R. Thompson, is 18 ft by 54 ft in front of the counters, while the lounge, which is also decorated by the same artist, is 42 ft by 40 ft. There is a sort of shopping arcade in and about the lounge, as in the up-to-date hotels, and it is quite big enough for tea dances or concerts. So comfortable, indeed, are the lounge and the bar at the Saville, that it is to be feared that something more than a warning bell will be necessary to clear them
The theatre was damaged by bombing in 1941, but reopened quickly allowing Up and Running by Firth Shephard to complete a run of 603 performances. In 1955, the interior was completely refurbished by Laurence Irving, and John Collins created a new mural for the stalls bar. In 1963, a musical adaption of the Pickwick Papers premièred on July 4, 1963, featuring Harry Secombe in his first role in a musical. It was a success, remaining in the West End for two years and going on to tour the US, with a run on Broadway.
Brian Epstein, manager of The Beatles and himself a former drama student, bought the theatre in 1965, presenting both plays (including works by Arnold Wesker) and rock and roll shows. The venue became notorious for its Sunday night concerts, during one by Chuck Berry members of the audience stormed the stage and the police were called to clear the theatre.
The venue also saw the last UK appearance of The Jimi Hendrix Experience (on 4 June 1967) before their groundbreaking Monterey Pop Festival performance. The Move and Procol Harum also appeared on the bill. Yoko Ono performed there in 1967, in front of a projection of her film Bottoms (Film No. 5), and using smoke machines to fill the auditorium. An eclectic mix of bands such as Nirvana, Cream, Fairport Convention, the Incredible String Band and The Bee Gees, also appeared there.
The Beatles themselves borrowed the Saville to make their "Hello, Goodbye" promo (an early music video) in 1967. While the promo did air in the United States, it wasn't allowed on British television because of a restriction on mimed performances.
Epstein died in August 1967, with the late show cancelled, as a mark of respect and soon after, the theatre was sold. In 1969, the theatre returned to presenting theatrical productions and under the new management it presented the London première of The Resistible Rise of Arturo Ui, a production that brought Leonard Rossiter to public attention. The last play to be performed at the theatre was Enemy by Robert Maugham, opening for a short run in December 1969.
The exterior of the theatre retains many of the 1930s details, although the wrought iron window on the frontage, has been replaced by glass blocks. A sculptured frieze around the building for nearly , remains and represents 'Drama Through The Ages'.