This has been studied extensively.
The UK is not the only country that uses the dialect you describe. Australia is another country that uses a similar English dialect.
I would argue that this gives credence to CSW being satoshi. With that being said, there is also plenty of other evidence that suggests that CSW is
not satoshi. Although it is difficult to prove a negative, I would say it is all but certain that CSW is in fact not satoshi, at least in my eyes (the evidence is overwhelming IMO).
As others have mentioned, it is possible this is all misdirection. IIRC, satoshi's posts were consistent with him living in the US, on the east coast, or having a similar sleep schedule as someone who lives there.