That's such an english thing to do. London is rightfully proud of The Blitz Spirit (despite it getting called out by atrocious people these days) and the inhabitants efforts to stay and not give up. The City or Country or Queen not giving up and somehow getting a solution out the end is a repeated trope that comes up in various media. Take a look at the small section on the UK inthe World War Z novel, for example.I had the feeling that there is also a certain pride in not giving up and having created something marvelous in the process.
Also Moonbark said their island is still sinking, it´s not about giving up Londinium, they would have to abandon England.