There are moments in fashion when you recognise something that will change the landscape of our fair industry. It happened at Jil Sander in September 2010 when Raf Simons transformed neon colours into a palatable concept with that skirt. But now, the new 'it' item has arrived, storming catwalks and constructed by the real who's who in fashion. If you are looking for the defining autumn addition then this is it. Seriously. Introducing, the trouser suit.