Manchester Business School has been around for quite some time. Not as famous as London Business School, but MBS is different as it has undergraduate degrees, like many other business schools that have been set up more recently, compared to MBS. You will note such business schools in many universities as the universities project their seriousness and emphasis in business and management related studies. I am not very familiar with KCL but the obvious is that Kings is famous for Law and may be on the way to building up their economics and management department, with strong demand from students for such degrees. The establishment of a 'Business School' is a signal to applicants and employers - Warwick Business School, Lancaster Business School, etc etc. But, I agree that big is not necessarily good, neither is it necessarily bad ... best to ask around for more opinions, perhaps on a Manchester thread.