But yesterday just below Duckworth Clough tip I had this very large full on yellow butterfly which flew at about 10ft high straight through on a course SE to NW with no deviation and it kept going, it was quite large in size of similarity to perhaps a large white though in this instance very lemmony/yellowy in colour, I mentally made comparison to either a Brimstone or Clouded Yellow of which I have been fortunate to observe on several occasions previously, but sadly on this I was unable to make a confirmed identification.