It looks very much as though the number of ova laid this year in and around Savernake Forest, Wiltshire, is slightly lower than in 2011 - which itself was a very poor egg lay year. I haven't finished the task of searching yet but doubt that I'll match last year's tally. The distribution of eggs and larvae in the forest is very different this time round, with several being found outside the forest.
Eight days of hot sunny weather from 22nd July, when the butterfly was at peak season, should perhaps have led to a better egg lay than this. But adults were in miserably low numbers here this season and the females do not actually like excessively hot weather.
Larval development is currently behind on the previous three years, which is hardly surprising given the late flight season. However, the sallow trees are turning autumnal unusually early. These guys need to hurry up! Here's a larva from today -