Raymond – I think that Tawny pinion looks a much slimmer moth on first impression. It is overall darker too, i.e the pale areas are a darker shade too unlike Pale pinion which also looks a more robust moth to me (broader wings). There are darker marks on the ‘crests’ on the thorax on Tawny too. Tawny certainly in my experience is the scarcer species, only ever had it once at IGC and only seen it a small number of other times whereas Pale is regular now after colonizing Suffolk in the mid 2000′s.