Little Moth.

[kevinj]

I know this because his wings are flat at rest.
He was having trouble hanging on as the wind was quite gusty.

[Alan]

There are always exceptions to the rule, but generally that is true.

The easiest way to tell them apart is by the antenna. Moths have a simple thread like or 'feathery' antenna without a club

Butterflies and Skippers have a thickened club or hook on the tip of the antenna - never 'feathery'