not really sure about UK punk, think it's been fairly underground since it's early years, I can't really think of (m)any punk bands from the UK that have been big. The US punk scene it certainly has plenty of commercially successful punks bands (Offspring, Green Day, etc) and any punk band I can think of just now is from the US.
I think part of it comes down to what you define as 'punk'.
US punk bands like Offspring and Greenday don't really sound much like the Sex Pistols or the Clash, yet they are punk all the same. Was punk about anarchy? I don't think so, that's just how the Pistols did it. Given the progression of music, I don't think we're likely to hear any new bands that sound particularly like the orginal Brit Punk (though Rancid come close I think, then again they have been around for some time now).
I think of 'punk' as an attitude, not a style. To give an example that I came across a while ago
----
A punk is trying to explain to his friend what being a punk is about
friend: "So if I go wild and cause chaos, that's being punk?"
punk: "No, you've got think for yourself, be free from the influence of others, do your own thing"
The punk then kicks over a near by bin.
punk: "there, that's punk"
The friend then kicks over another near by bin
friend: "So that's punk!"
punk: "No, that's trendy"
----
You either get it or you don't.
Then again, by my definition, a lot more music/bands would be classed as punk... Motley Crue, Guns'N'roses and so on, most 80s metal embrassed the values I see in Punk, and there is still plenty today that does. On the other hand, Punk could not be immitated, as imitation alone excludes it from being punk!
Of course, people have a tendancy, particuarly in the UK, to exclude things (from any particular genre) on the basis that it has been successfully commercial... some people like to be a cliche, the want to be 'underground' and not be associated with mainstream. To give an older example, a girl duo called Shampoo had great commercial success with "Uh Oh, We're in trouble", they were wild and certainly appeared to be 'punk' in personality, attitude and musical style, however due to commercial success they were dis-owned in a manner of speaking.
Interstingly, a search on google provides a few definaitions of 'punk'
http://www.google.co.uk/search?hl=en&lr=&safe=off&oi=defmore&defl=en&q=define:PunkThe most straight forward definition listed is "Punk Rock is an anti-establishment music movement", seems to sum it up well.
On that note, it probably helps explain why there are relatively few 'known' punk bands in the UK now. There was a lot of social unrest in the 70s when the scene began, things are not the same anymore and as people have got used to it and 'desensitised' to the shock of punk rock, the same impact has faded as it isn't new to everyone. Add to that, trends change and Punk was a trend back in the 70s, then consider that when something is a trend, it will get more effort and attention from the music business - if you add more effort and production values to punk music, does that not dilute what was actually 'punk' about it in the first place?
Most people are most 'anti-establishment' during their teens, so maybe that's why punk is often seen as 'for kids' (though I strongly disagree) these days.
As a generalisation, I think that there is little difference in musical sound between rock/metal and what is called punk now. I just think of modern punk music as metal with a sense of humour!
Maybe not a direct answer to your actual question, but maybe it will prompt some discussion
