Britain’s leading investors sent out a stern warning to boards on Thursday that they take a dim view of the hefty retention bonuses increasingly offered to executives who have been passed over for the top job.

More than a third of BP’s shareholders failed to support last year’s executive pay packages at the oil company’s annual meeting, a level of protest seldom seen in the UK. The revolt was caused by one-off bonuses proposed for two executives, passed over for the job of chief executive.