Btw - those big black flies we saw and felt hitting our faces and helmets are St Mark's flies... So called because they appear at about St Mark's Day the 28th April!! Also those ones with the dangly legs are the males - the females tuck their legs in when they fly (sounds a bit like my commute with the way some blokes sit ).
I did manage to swallow one of their smaller cousins though I think I might have managed to spit out - that's when I was coughing after the top of Tilburstow Hill. Probably could've done with the extra protein to get home...