If your mum was anything like ours when MR PORTER were a lad, she was obsessed with “feeling the benefit”. Which in our household translated to not even thinking about wearing a coat until it was absolutely necessary to do so, and certainly never indoors. A rigidly enforced rule that is scientifically questionable – it’s a hot topic for the colder months – and more importantly, leaves you exposed to being, well, left exposed once the winter really sets in and there’s a run on outerwear. So, while not wanting to contradict an authority such as your mum, our recommendation is to pull the trigger now. And if you haven’t even started to choose yours, you’d better.