When I moved into my current house, in Sully, on 3rd February, 1994 the very first bird I saw was a male Blackcap. I have seen the bird (or more likely a relative) every 3rd Feb since then. I did notice one a few days ago, so they are around. Most I have ever seen in the garden in winter was 3 – including 1 female.
I see Blackcaps in my garden (as this one today) once or twice at some point during each winter and generally male; as lolmid points out “they are around”.
Glamorgan Bird Club 
When I moved into my current house, in Sully, on 3rd February, 1994 the very first bird I saw was a male Blackcap. I have seen the bird (or more likely a relative) every 3rd Feb since then. I did notice one a few days ago, so they are around. Most I have ever seen in the garden in winter was 3 – including 1 female.
I see Blackcaps in my garden (as this one today) once or twice at some point during each winter and generally male; as lolmid points out “they are around”.