Elisabeth Maugars joined the London office of Deutsche Bank in 2015, when she was 52.

Ms Maugars, who was paid a salary of £295,000 a year, said she was the victim of “a culture of sexism and ageism” and bullying by colleagues before she was made redundant.

An employment tribunal heard that her fellow bankers called her Christine Lagarde — the president of the European Central Bank who is also French and has grey hair.

Ms Maugars said the office was a boys’ club that discriminated against her as an old woman who refused to dye her hair. She sued for £4.6m after being made redundant.

All her claims — for unfair dismissal, age discrimination and sex discrimination — failed after it was ruled she had been treated fairly.

Judge Bernice Elgot said that being nicknamed Christine Lagarde was “part of the irritation of day-to-day office life which occasionally occurs”.

She was dismissed on the basis that her US counterpart had generated £29m in business over the previous year while she had brought in a mere £6m.

The ruling stated that the bank needed fewer employees and that Ms Maugars had been “fairly and reasonably selected for redundancy”. It acknowledged that the decision was a “crushing blow for her but it was not sex or age discrimination”.