JPMorgan’s top executives have embarked on a charm offensive to allay fears by staff and regulators that the ousting of Bill Winters as co-head of the investment bank will mean a diminished role for its London operations.

Jamie Dimon, JPMorgan’s chief executive, made a surprise visit to London last week, meeting about 70 senior managers, to reassure them that the City and Europe remain crucial to the bank’s future, the group said.