Credit Suisse also reported that the mean hourly gap had tightened by 10 per cent year-on-year, which came in at 39.2 per cent. Bonus pay showed large differences, as the bank logged a median bonus pay gap of 56 per cent for 2017, down by 3.1 per cent. The mean bonus pay gap was 70.2 per cent for 2017, down from 75.8 per cent in 2016.

Peter Goerke, the bank’s senior human resources officer, told the Wall Street Journal that women made up just 14 per cent of managing directors globally as of the end of 2017, up from 11 per cent two years earlier. 

In a bid to close the pay gap, he said Credit Suisse has "aspirations" -- not hard targets -- of around 18 per cent female managing directors by 2021, and increasing the proportion of director-level women to 27 per cent that year from 23 per cent at the end of 2017.

The bank’s median pay gap was rather small compared to other banking institutions’ operations in the UK – including JP Morgan (54 per cent), Schroders (44.8 per cent), Barclays (43.5 per cent) and Lloyds Bank (42.7 per cent).

Controversy over the issue comes as sectors such as wealth management are, practitioners say, trying to improve the working environment for women, particularly as retaining and hiring female staff is seen as important when more women are wealth holders.

Earlier this month, this publication reported that UBS, Goldman Sachs,Invesco, Danske Bank, LGT Vestra, Hargreaves Lansdown, Man Group, Investec Wealth & Investments, Brown Shipley, Brewin Dolphin, Bank of Ireland and Cameron & Company Financial Planning had signed up to the Women in Finance Charter.

More than 200 firms have now signed the Charter and over 650,000 employees in the UK are covered by its plan to tackle gender inequality in financial services.