In PR terms, it’s a such a well-worn trajectory, it has its own name. ‘Doing a Burberry’ is the term for when something once exclusive and favoured by those in-the-know is appropriated by the hoi polloi and its standing slips inexorably downwards. The Ivy — now a chain of naff provincial cafés — is a notable victim. Marbella, now ‘Marbs’ thanks to the cast of TOWIE is another. So is the name Samantha, once terribly Sloaney, now associated only with a