Cronin, previously COO, will continue to head up Gavin Anderson's Global Energy and Environment practice.
Cronin led the Gavin Anderson team during last year's Eurotunnel restructuring and continues to manage the global Gazprom account. He spent a number of years in investor relations at British Energy, following finance roles at Ladbrokes and British Gas, before joining Gavin Anderson in 2003.
Deborah Walter, a 20-year veteran of Gavin Anderson, has been appointed COO.
Walter's key accounts include advising Alliance Boots, including its private equity deal last year, and the Department for Business, Energy and Regulatory Reform.
The moves come after London CEO Fergus Wylie was made executive chairman, Europe (PRWeek, 1 February).
'London continues to be our key office as we see increasing cross-border opportunities,' said Wylie. 'Ken will drive our UK-focused business as well as ensuring we meet the aspirations of international clients.'
Cronin said the firm would not be looking for any specific replacement staff.
Gavin Anderson has picked up some high-profile clients in the past year, including House of Fraser, which ended a five-year relationship with Brunswick in March.