Female robins look pretty much the same as males. The juveniles, however, are very lovely little speckedly creatures.

Also, you don't often see more than one robin in the same area as they're territorial.

The RSPB's got some nice concise info: https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/robin/territory/

I envy you the blackcaps: I don't think I've ever seen any.