Large Skipper (Ochiodes venata)
The Latin name 'venata' gives a clue as how to identify this butterfly as it has a dark, almost black vein running across the fore wings. It is also rather patchy, an orange and brown pattern whereas the other common skipper, the Small Skipper has a much more consistent orange all over the wings with a dark border.
The male Large Skipper can be quite territorial, a bit like a dragonfly, settling on a prominent piece of vegetation in the middle of its patch and then swiftly launcing itself to deter intruders.
The food plant of the Large Skipper larvae is Cock's-foot and Slender False Brome, both common grasses.