Puzzle solved.
Through this week I have been a bit puzzled as to why I have had a few red mites on my hands every now and again especially as I haven't been handling the chickens etc.
I've been collecting eggs though and assumed I had picked a few up there even though I couldnt see any at all when I looked.
Then today, still getting a few red mites but I havent been collecting eggs & partner not noticed any either - then it dawned on me that I had been digging through the week and the little itchy buggers are in my gloves from a cockerel dispatch a few weeks ago which was in a different pen. DOH!!