Hi Simonbengeo, mine gets this too. I think it's where the cold weather damages them slightly, mine are usually okay though, they'll have a bit of damage on them as they grow but it won't affect the plant.

It seems to happen most to fairly newly planted items and/or where they're in a windy or exposed site.
It happened when mine had only been in the ground a few months before the winter set it .... going back about 2 years now. It doesn't seem to happen much any more though, now that they're more mature.

Hi Simon this happened to mine too.I've tried cutting out all the affected leaves, (reducing the shrub to twigs !) and leaving alone.Both methods having the same end result-it cleared up itself by late spring with glossy leaves as if nothing had happened ! I would say though ,give it a seaweed fertiliser in spring especially if it is in a pot as is mine,the less stressed out it is the better it will cope :)