had a week up in the lakes a few weeks back for once we had good weather its normally windy and rainy and we discovered the down side of good weather in the lakes – Horse flies , I made sure any routes we did had minimal slow sections as whenever we were moving slow the buggers were biting, also noticed the feckers like to hang around gates – so whenever we had to stop at a gate we got bitten
The odd thing was their bites didnt swell up a lot, for me where as horsefly bites on the surrey hills leave inch long red welts on me
We also had a coupe of days in the Peak District and yorkshire but didn’t get bothered by horseflys so much there – but there was a bit more wind on those days