Before now, the only time I mixed black and navy was when I accidentally put on the wrong colour tights on a dark, miserable Winter morning. Mixing these two shades was always a big 'no' growing up, one of those fashion rules your mum taught you early on.

But this season, this unexpected combination has become super-chic with loads of designers (including Preen, Carolina Herrera and Cushnie et Ochs) pairing black and blue to great effect. The key is to do it on one piece, so it looks deliberate, and keep your navy a bit brighter than your average school uniform.

Mango has done us proud in the outerwear stakes with this coat, a great suits-all classic shape with cool zip detailing and a convertible collar design that can be worn two days. It's £129.99 and would look great styled just how the Mango team have done it, with dark jeans and black boots.