You need to look at net salaries after taxes. And for CoL it depends on what your consumption basket is. My cost of living would be higher in London. (I lived in both places.) I don't drive, I don't smoke, I use public transport a lot, and I pay for household help. I do drink beer, which is expensive in Singapore, but it's a small part of my overall budget.

I save a lot of money on 0% capital gains taxes here.

I regularly check London jobs and interview for them, but the numbers haven't made sense so far.