I did not have long so I had a go at two areas, one up on the ridge and the other down low on the slope down to Sandy Lane. The technique with these is apparently to put all the debris that ends up in the net into a box and wait for the larvae to climb up the sides and reveal themselves.
My collection of sweepings from the ridge produced two cases each of Coleophora juncicolella and Coleophora pyrrhulipennella - neither of which I have seen before - so, I felt, an hour well spent.
Common Heath, Esperia sulphurella and Cydia succedana.
As a Post Script to this, I inspected my box of sweepings again this morning and I was surprised to find another 10 juncicolella larvae had evaded the spiders and emerged from the debris. I had been through it yesterday under a microscope and didn't find any! So if you are trying this, let the sweepings sit overnight because these larvae can sit around immobile for quite a while.