Bonuses for junior investment bankers in London have increased by as much as 10% on average — sometimes at the expense of their superiors — as firms battle to keep hold of their most talented young staff.

Analysts and associates working at the big US investment banks are the highest-paid in London, according to a report from the recruitment firm Dartmouth Partners, which looked at the mean salaries and bonuses awarded to bankers in the early years of their careers.