It should be the perfect corporate broking client. It is the largest company in the FTSE 100 by market capitalisation and has bought and sold around £190 billion of assets over the past decade, according to data provider Dealogic. Last year it acquired BG Group in a $50 billion deal. The problem is Royal Dutch Shell does not “see the need for a corporate broker”.

The company's stance - coupled with the fact that BG's own brokers were not the main advisers to their client on its takeover - highlights the challenge facing investment banks. How much effort should they put into building relationships that offer no guarantee of work?