This species is not local to the Yeldham area. The nearest sites are in south Essex, extreme north-west Essex, Hertfordshire and in Cambridgeshire.
2011 had a hot dry spring and was generally about 2 weeks early for butterflies. I saw some in mid June at Woodwalton Marsh and on the Devil's Dyke where it crosses Newmarket Heath. On July 15th they were still flying on Magog Down a few miles east of Cambridge, but not looking very fresh.

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 upper row of photographs above. As soon as the cloud passes they become active, stopping briefly on flower heads to take nectar. There is a small population at Woodwalton Marsh where I saw about six adults on 16 June 2011.