When the world's largest asset manager decides to issue guidelines to FTSE 350 companies about executive pay it is hard not to pay attention.

BlackRock is no stranger to offering advice to the market. Chief executive Larry Fink has sent a few helpful notes. There was a letter to investment banks in 2011 advising them how to market IPOs to shareholders, and last year, another to S&P 500 bosses urging better corporate governance.