Cast your mind back some 15 years, if you can. Gordon Brown was in office, the corporate world was reeling from the first effects of the global financial crisis and Kirkland & Ellis' revenue had only just about broken the $1 billion mark—its subsequent domination of the legal industry was a decade away. 

A lot has changed in that time. But most lawyers would have you believe that client relationships can and should persevere through all manner of change. Indeed, Freshfields Bruckhaus Deringer has advised the Bank of England for nearly three centuries while Farrer & Co has remained steadfast advisers to the British Royal Family for nearly 100 years.