I guess that makes sense - in the EU a masters degree is usually required for a PhD which is not the case in the US. That accounts for 1-2 years at least.
Yes. The standard "1+3" funding programme covers a 1 year MRes or other masters degree with methods training in advance of the PhD programme starting. I got mine separately, so just had "+3" funding. Like in the US, a PhD without funding is normally a bad idea.
Edit: It generally remains shorter than a US programme, though. We tell ourselves that our focused BA/BSc programmes provide a better foundation than the broader US undergraduate degrees, but I suspect the truth is just that it's cultural differences.
I was very lucky to not need a masters, 3 years BEng and then 3 PhD. I couldn’t have done another year. I was dying to get out but the end. My wife did 3,1,3 and I have no idea how she did that extra year.
Edit: It generally remains shorter than a US programme, though. We tell ourselves that our focused BA/BSc programmes provide a better foundation than the broader US undergraduate degrees, but I suspect the truth is just that it's cultural differences.