Stuart here has quite a simple outfit, a plain T-Shirt and trousers. But, by tucking the T-shirt in and adding the belt it gives it a touch of cool-nerd or geek-chic. These are the type of trousers you would call 'slacks', old fashioned yet when deliberately cut short like this look contemporary. By wearing black socks and shoes he doesn't make it too obvious and even though the colourings seem quite dull for Summer they suit London.
Trousers & T- Shirt - American Apparel, Shoes - Dr Martens