Even sharing in a huge profit does not prevent bad blood between rival brokers. Two weeks ago, Deutsche and Goldman handled what is thought to be London's largest ever block trade - the sale of a £3.2bn slug of Vodafone previously owned by Hutchison Whampoa. The two banks carved up the major clients between them but that left other smaller potential buyers to fight over.

According to a Deutsche broker, the two rivals agreed to start selling the shares at 10am on Wednesday March 22.