Brimstone.
(Opisthograptis luteolata)

A Brimstone moth resting on my garden wall.

Information:
One of the easiest moths to identify with its overall yellow colouring and dark brown or red marks on the leading edge of the forewings. It has prominent eyes and a furry chest, brown knees and very pale legs. The size range is 14-21mm, the female, as is often the case, is larger than the male. They can be seen any time between April and October.