I went through all of the photographs on this blog to see if I could see one already recorded. The head and upper thorax was as black as pitch and I began to wonder if it was a moth and not a sawfly or a species of caddis. The Lewington guides were riffled through as was the Yorkshire website but I couldn't spot its like. Fortunately an email to Charlie Fletcher was responded to and the moth was identified as a poorly marked Diurnea flagella the 'daylight-flying, lover-of-beech-trees'.
March Dagger is species number 426