This species is not local to the Yeldham area. They can be found in the south of the county with a good population on Canvey Island. In Cambridgeshire I have seen a few on Magog Down near Cambridge, on the Devil's Dyke and at Woodwalton Marsh.
The Marbled White has only one brood per year. The larval food plants are various fine-leaved grasses, and it over-winters as larvae. The adults are on the wing from late June to early August.
In overcast conditions the butterflies perch for long periods in full view on grasses or other plants with the wings either closed or held flat open as in the first three photographs above. As soon as the cloud passes they become active, stopping briefly on flower heads to take nectar.