My first role in legal PR was for the long forgotten Wilde Sapte - a banking and finance firm.  It is perhaps now best remembered for almost jumping into bed with Andersens. 

The fall out of that failed courtship led to Wilde Sapte falling into the Denton's bed.  Many at the time argued that the Big Four (then Five) would be best to leave the legal market alone. 

This article - with a terrific infographic - charts the fall and rise of the Big Four accountancy firm's attack on the global legal market. 

They bring true international reach, a strong brand, and an attractive multi-disciplinary offer.  Few law firms can compete. 

Perhaps the real threat to Big Law comes not from within itself, but from the bean counters.