“I’m a woman designing for women, and there are so many layers to that,” McCartney says. “On the one hand, it brings an effortlessness but it also means that I think and overthink every detail, whether it’s physical or mental or even – in some sense – spiritual. I can debate for weeks whether a trouser should sit on the waist, or a centimetre below, or on the hip, whether it should have a zip or a button, because I find personally that a detail like that can have a massive impact on how I carry myself that day. If I wear a slouchy jean, that will affect my posture and my whole manner. What I’m projecting will be a reflection of that waistband, a detail you might not even notice.