I am the Butterfly Conservation transect walker for Bearshank Wood, which is approx one mile east of Fermyn Wood. I am pleased to report multiple sightings of Purple Emperor males this summer. I believe this is a new venue for the species?
Although I only recorded four on my weekly "official" Transect walks (two each in weeks 14 and 15, ie on July 4th and 12th), I spotted several more (up to six in a hour) on other visits during that brief "window" of fine weather in early July. I did not see any after the middle of July.
A retired friend of mine who is a keen ornitholigist also told me he had seen several Purple Emperors (again all males) during his early morning (approx 9am - 10am) daily wlaks around Bearshank Wood. This was the first year he had seen them, in 30 years of visiting the place on a daily basis.
Bearshank Wood was mainly coniferous until about 12 years ago, when they were cut down and replace dby indigenous trees (mainly birth and oak saplings). However, sallow has become very prolific in many areas, particularly (and convemniently!) close to the nearest vehicular access point. This is also where I enjoyed most sightings, on the track (flattened hardcore/gravel) that runs into the wood.
I believe it is a Forestry Commission wood. It is controlle dby a shooting syndicate, but I know the gamekeeper quite well and he appears to be conservation-friendly. I mentione dto him the importance of not cutting back the sallows!
It is close to Lyveden New Bield, a National Trust property, where I have photographed some lovely SW Fritillaries this summer and which I'm sure Matthew must know well. (Lyveden is situated midway between Fermyn and Bearshanks)
I hope the above information is useful. If you require any more, please don't hesitate to ask
Caroline Cottage, Church Street,
Nr Oundle, Northants PE8 5ST