I spent a couple of hours at Ivinghoe Beacon on the flowery slope above the Duke of Burgundy site which was alive with Dark Green Fritillaries. I don't ever remember seeing so many before. Also good numbers of Ringlet, Marbled White and Small Heath butterflies.
Here are a few photos I managed to grab in the rare moments when they settled on Knapweeds. One shows a very strongly marked female (Charlie Jackson)