Summer Visitor Staying for Winter?

I read awhile ago on the RSPB site that Blackcaps were being seen more and more overwintering in the UK. I just assumed it would be down South where the winters aren't quite as harsh as they can be in Yorkshire so was surprised to see a female enjoying the berries on the trees near my home. I've never noticed one in the area before so to see them here at this time of year was a very pleasant spot this morning. Its quite a suburban area with lots of big gardens and plenty of feeders around so there must be enough food to see her through till Spring.