Clouded Border (Lomaspilis marginata)
Although a night flying species the Clouded Border is one of those moths that you frequently encounter by day as they seem to be light sleepers! It is not uncommon to be walking through woodland or scrubby places and see a white coloured moth fly up. It will not always be a Clouded Border, as other geometrid moths are easily disturbed too, but if you are able to keep your eye on them and watch for where they settle you will often get a good look at them as they try to go back to sleep.
The Clouded Border is quite common down here in Dorset flying in June and July. It is comfortable in many habitats including heaths, common and marshy places as well as woodland and scrub.
One word of warning, the wing markings can be quite variable in terms of black markings so the one you find might not look exactly like this one!