As the debate over competition and choice in the larger company audit market gathers pace, one area that demands attention is just how many former Big Four – PwC, Deloitte, EY and KPMG – partners and staff are now sitting in the boardrooms of the largest listed companies in the UK.

For not only have these giants of the auditing market achieved an oligopoly in the supply of audit services, they have also as good as sewn up the demand side, claiming almost two thirds of the FTSE 100’s CFOs and audit committee chairs as their own.