Ernst & Young

The E&Y building

Ernst & Young is the baby of the Big Four, but a big baby. The UK firm turned over just over £1bn in 2006, and it is comfortably ahead of the largest mid-tier firm, Grant Thornton.

Based by the Thames near Tower Bridge, in probably the smartest of all the Big Four offices, E&Y boasts 470 partners and 8,000 staff. Around a half of those are in London.

The firm is currently led by Mark Otty, a tall South African in his early forties and a jogging fanatic who ran the 2007 London marathon in just over 3 hours.

The firm's highest profile audit client is BP. The oil giant paid E&Y $73m (£36m) for its services in 2006 alone.

Historically, E&Y was formed out of the merger of Ernst & Whinney and Arthur Young in 1989, themselves developed through a series of mergers stretching back over a century and more.

Its international network, like those of the rest of the Big Four, takes some explaining.

To the outsider, its shiny offices and logos stare uniformly at you in every major city across the world. But each country has its own legally separate firm. Profits are shared in the UK between UK partners, however much lead generation they may get from overseas.

The firm is global in that some of those partners responsible for increasing revenues will be remunerated according to global, and not UK growth, but it is by no means a seamless international outfit.