Still:
China 8.0
UK 5.6
Sweden 4.5 (my country)
Since China is vastly overpopulated, the raw emissions and thus the real-time footprint is the real problem here. They and the Americans are the worst on that front, no contest.
It's not just Co2 they're dumping either, they have some of the worst air pollution in the whole world through no environmental regulation. It's beyond me why anyone in any Green party still advocates trade with China.
Population densities (per square kilometer):
UK: 274
China: 145
Sweden: 23
Germany: 223
USA: 34
Co2 emissions 2017 - tonnes per capita/year (percentage change compared to 1990):
UK: 5.7 tonnes (-35.6%)
China: 7.7 tonnes (+353.8%)
Sweden: 5.1 tonnes (-12.5%)
Germany: 9.7 tonnes (-21.8%)
USA: 25.7 tonnes (+0.4%)
A much more complicated picture than you outlined. I am struggling to understand why you single out China as being over-populated when the UK has nearly twice the population density. I do support the idea that (world) over population is the primary cause/problem with climate change, but why point to China when the UK has nearly twice the density?