The GDP of London is significantly larger than that of sever 20 4, 7:27pm

London produces 22% of the UK's $2,749 trillion GDP

https://en.wikipedia.org/wiki/Economy_of_London
https://en.wikipedia.org/wiki/Economy_of_the_United_Kingdom

... which would be about $604B USD. Sweden's GDP is $570B and Belgium's is $535B:

https://en.wikipedia.org/wiki/List_of_sovereign_states_in_Europe_by_GDP_%28nominal%29

Verdict: True