What is the reason for most Cafes closing before 6pm in the UK, especially in London?

In Europe it is quite common to meet a friend for coffee or tea and cake in the afternoon/early evening, and in bigger cities it possible to find a cafe open until 10 pm or even later. They usually sell desserts and coffee/ tea and are seen as a normal way to socialise, when you are meeting a friend or going on a date. I've lived in London for many years and it is difficult to find a place to sit down and read/ or meet a friend for a quiet chat and tea after 5 pm. What is the reason for that? Is there a licensing issue at play? I don't really understand why cafes would miss out on business otherwise.