If their hair is wet or matted they won’t have the insulation ability of a dry and fluffy coat.It's pretty unlikely that temperatures in the UK are likely to cause cows to struggle to stay warm. Dairy crosses do tend to be softer, but I'd have thought the Hereford would add a tough enough hide to hack our conditions.
BB tend to be thin skinned and lean, so can struggle.
A cow in the UK shouldn’t be losing the 1-3 lbs a day that cattle here can potentially lose, but that doesn’t mean they’re gaining or keeping condition either.