Joan Ingpen was the founder of the artist management agency Ingpen & Williams and an important and influential figure in opera administration. As a planner for a number of the great opera houses from the 1960s to the 1980s she was renowned for her impatient efficiency — one colleague referred to her “hard-edged diamond brain”. She championed long-term planning, and was also known for precipitating the rise to fame of Luciano Pavarotti (obituary, Sept 6, 2007) in 1963, when she booked him to cover for the role of Rodolfo in La bohème at Covent Garden, in case Giuseppe Di Stefano was unable to perform. Di Stefano withdrew on the second night.

Ingpen was born in London in 1916. Her father disappeared when she was little, having been sent to Russia on a government mission before the Bolshevik Revolution. She became an accomplished pianist and a licentiate of the Royal Academy of Music but did not want to be a performer. Instead she learnt to type and worked as a clerk with a marine insurance firm.

She went to as many concerts as she could, though, and was introduced to Walter Legge at EMI. Later, when he was head of the “good music” section of the Entertainments National Service Association, he asked her to join him there, which she did. After the war she helped him start the Philharmonia Orchestra. “I did the boring side while he did the musical side”, she said in 2005. “But then he took over entirely. In fact, we fell out. He was a very strange man — wonderfully enthusiastic to work with, but he had to be emperor.”

Ingpen founded her agency in 1946, the “Williams” in the name being her dachshund. Among her clients were Georg Solti, Rudolf Kempe and Joan Sutherland, whom she spotted in 1953. After her marriage to an Austrian agent, Alfred Dietz, she became more closely involved with opera. One day Solti rang her and asked her to sell her business and go to Covent Garden. “I thought I’d much rather do something constructive,” she said later. “I’m not a saleswoman really, which, let’s face it, is what you are as an agent.”

On taking up her role as controller of opera planning at the Royal Opera House in 1962 she was horrified to find that little was fixed beyond the coming season. She set about extending the plans to two or three seasons.

“You have to leave some holes,” she said. “Some singers come up, some go off. It’s a very painful thing to tell a singer that you have to pay him off, but singers do have crises. To get the singers you wanted, it was essential to work ahead of the other houses, but sometimes that meant things could be pretty awful by the time they arrived . . . I feel very much for performers, and, at least if they were in the company, I tried to give them less important roles. Really, what I liked most was helping people to perform. I just happen to have a mind that can do the details.” One of her coups was engaging John Dexter, admired for his production of Peter Shaffer’s play The Royal Hunt of the Sun, to direct Berlioz’s Benvenuto Cellini. It was his first foray into opera.

Her years as an agent had given her a good grounding in diplomacy, and she was well able to deal sensitively with artists, and indeed with Solti — “We called him ‘Soltissimo’, because he always wanted everything yesterday. But he wasn’t difficult, provided you were quick.” Such was Solti’s admiration of Ingpen that when he was asked to join the Paris Opera as musical adviser he said he would accept only if he could take Ingpen with him — and Rolf Liebermann, the general manager of the Paris Opera, was obliged to visit her in her country cottage. She accepted the position of director of planning, and she and Solti were installed in Paris in 1972. Some attributed to Ingpen the high proportion of British singers performing in Paris in the years that followed. “British musicians score hit in Parisian musical life”, ran a headline in The Times in 1976, above an article which referred to the“quietly spoken English woman” who was Liebermann’s key assistant.

In 1978 Ingpen accepted the position of artistic administrative director at the Metropolitan Opera, Plácido Domingo having recommended her to the music director James Levine. (Dexter was by then the Met’s production supervisor.) Once again she much improved the planning systems, while adapting to a more conservative approach in deciding the schedule, which meant consulting the general manager and bargaining with the box office. (In quiet moments before performances, away from what she called the “rough and tumble” of the opera house, she enjoyed a quiet game of patience.)

In 1981 Tony Bliss became general manager and Ingpen one of three assistant managers, the others being Marilyn Shapiro and Joseph Volpe. Ingpen left in 1984 and three years later became a talent-spotter in Europe, a notable find being Anne Sofie von Otter. She retired in 1987, and went to live in Brighton and, latterly, Hove.

Ingpen was criticised by some for an inflexible and dehumanised approach to planning and casting. But she had warm relationships with many artists (she wrote a touching tribute to Issay Dobrowen after his death), a lively sense of humour and clear musical preferences: “I would say Kirsten Flagstad and Tatiana Troyanos . . . For a tenor, well, Plácido’s pretty good, but for a different kind, and this is going back a bit, there was Julius Patzak. Even when he was past his best, his Florestan was something you could cry at.”

Ingpen was twice married. Her third, long-term, partner was the actor Sebastian Shaw, whose surname she took. He died in 1994.

Joan Ingpen, opera administrator, was born on January 3, 1916. She died on December 29, 2007, aged 91