Deloitte’s mean pay gap is 18.2%, while the firm’s mean bonus gap is 50.9%.

At the end of June, PwC was the first professional services firm to release its statistics. PwC’s mean gender pay gap is 13.7% and its mean bonus gap is 37.5%.

Deloitte says its pay and bonus gaps are due to the lower proportion of women holding the firm’s most senior roles, an issue that it is working hard to address. Once this structural issue is removed, the Deloitte mean pay gap reduces to around 2.5%, the firm says.

Emma Codd, managing partner for talent at Deloitte UK, said: ‘As with many organisations, Deloitte’s gender pay and bonus gaps arise because of the disproportionate number of men in senior positions.

‘As of 1 June, 19% of our partners were women. This is our most senior – and therefore highest-paid – grade. 29% of our directors – our second most senior grade – are female.

‘We have put in place a number of actions and initiatives to tackle this disparity, and also maintain our relentless focus on ensuring that we have the appropriate culture and working environment. We believe that the latter is critical to our success in truly addressing gender equality.’

Deloitte has introduced targeted initiatives such as a programme designed to develop and retain high potential female managers, a review of its recruitment processes, an industry-first Return to Work programme (open to all but with the aim of helping senior women return to work after a career break of two years or more) and a Working Parents Transitions Programme (designed to ensure a smooth transition to and from parental and adoption leave).

Codd said: ‘We know that meaningful and sustained change will take time and hard work. We are recruiting more women at both student entry and experienced hire level, and we are seeing a significant decrease in the number of women leaving the firm after they return from maternity leave.

‘However, the data we publish today is a clear reminder that achieving the gender balance we should have will take time and consistent focus.’

Under the new rules private, public and voluntary sector employers with 250 or more employees are required to publish their gender pay gap and bonus pay gap by April 2018. The regulations will cover approximately 9,000 employers with over 15m employees, representing nearly half of the UK’s workforce.

According to government figures, the UK’s national gender pay gap is currently 18.1%, the lowest since records began in 1997.