Secretaries in the Civil Service, Ida and her sister Louise spent most of their meagre salaries on opera tickets. A constant presence at Covent Garden, the pair became close to some of the greatest singers of the era and it was through Austrian conductor Clemens Krauss that Cook learned of the persecution of European Jews.

From that moment in 1934 until the outbreak of war, she and her sister helped Jews to safety. With reputations as opera obsessives, the sisters travelled back and forth to Germany under the pretext of hearing a favourite star, interviewing Jewish families desperate to escape, attending performances and on their return carrying the families’ valuables into Britain. Krauss assisted them, even arranging to perform in cities they needed to visit.

The sisters helped 29 people escape certain death, funded mainly by Ida’s writing. In 1965, they were honoured as Righteous Gentiles by the Yad Vashem Martyrs and Heroes Remembrance Authority in Israel.