in answer to foxy, i hatched almost all these birds from eggs in the last couple of years, the last chick i bought 2 yrs ago. they are mostly cream legbar, appenzeller and campine plus a sd welsummer and bantam welsummer, with a couple of (mistake but pretty) crosses. so i presume any mites/lice or whatever will have come from the frequent visitors to their field, pidgeons, crows and magpies. there were also rat burrows nearby, and they certainly visited so i don't leave any food out overnight now. they were sorted about a month ago. the cockerel is 2 yrs..
i recently treated for scaly leg mite, particularly the cockerel by using nettex spray once then dipping legs in veg oil most evenings for a couple of weeks or so. it was during treatment i noticed the bare reddish inner thighs of cockerel and sprayed with cyclo thinking might have been irritated by scaly leg mites or oil and though i could no longer see colour! as feathers were growing thought it ok. i found the skin problem when i was checking the 'another hen' for missing feathers on her back but as they were broken not 'fallen out' i'm sure they were caused by a young cockerel coming of age and a bit keen! (he's now gone to a new home and not causing any problems there). so oily look to feathers could still be residue from dipping legs in oil. i haven't used the eprinex yet but i think i'm about to as it would sort northern mite and lice (which others with good skin have), and any other creepy crawlies i believe.