Oliver Spencer's fishtail trousers are so-called because of the v-shaped cut in the rear of the waistband, which creates a more comfortable fit. They are a modern flat-fronted trouser with a gradual taper from the mid-thigh that will go with virtually everything you have in your wardrobe.  This style is cut from a lightweight tropical wool, and is great to style with summery knitted polos and short-sleeved shirts.