I'm a big fan of the Adidas three-stripe old-school zip-up tracksuit tops. I've got several for everyday wear, including an olive-green one, a burgundy one and a cream one with leather arms.
Plain white T-shirts do it for me every time. You can spend anything from £3 to £50 on a T-shirt, but I've bought some great ones from H&M, as well as shelling out on Duffer Of St George and a Polish label I discovered while filming 'Robin Hood' in Hungary called Scotch And Soda.
