Nothing says "effortless cool" like the grey marl t-shirt. It's neutral tone and relaxed look mean that it is the perfect partnering piece to your favourite black skinny jeans, jewelled skirt or leather shorts. The marl tee is timeless and the majority of high-street retailers carry their own version. I have at least four, in varying shades, and shapes - but the general theme is a round neck and slightly fitted. My favourites are from American Apparel - soft and great quality.
Depending on how much you have to spend, there are also adequate versions at Topshop, Primark, Whistles, T by Alexander Wang and Helmut Lang. A wardrobe staple!!!