Willis Towers Watson President and Deputy CEO Dominic Casserley will leave the group at the end of December, a year after helping to orchestrate the merger of the two companies.

Mr Casserley joined Willis as CEO in January 2013 – a position he kept until its merger with Towers Watson in January this year.

At Willis he oversaw the “analytical broker” and “connecting Willis” strategies, introduced industry specialisation, deepened broking capabilities and re-engineered core processes, contributing to a shareholder return of 58%.

In that time Willis expanded into healthcare advisory and brokerage, executed a partnership with Miller in London and acquired French broker Gras Savoye.

Mr Casserley, whose contract expires at the end of the year, is on the board of Willis Towers Watson, co-led the integration process and has led one of the global business segments – investment risk and reinsurance.

“I have great confidence the leadership team will carry Willis Towers Watson forward to new heights,” he said.