That’s funny. I was a California punk. And they sound English to me.
And the dim recollection gets a little brighter (though still not gospel). IIRC there’s been many examples of aphasics who loose the ability to speak fluently but can still sing just fine. In these cases, it’s generally Broca’s area that’s suffered the damage but other parts of the brain are still fully functional (warning: I’ve oversimplified for the sake of argument). I went looking for the specific areas that might be involved in singing but alas, the library’s closed and I can’t turn up anything on the net that doesn’t involve songbirds. However, I did come across this article that discuss a few case studies of people with amusia. Pretty neat stuff actually.
On the other hand choir boys and girls always sound british no matter where you are. I remeber being yelled at once for saying “garden” or something like that instead of “gaah-den” or “our father” instead of " awe fathah".
Hermits Hermits always sound very british to me. I’ve heard that the Ramones tried to copy there vocal style when they first came out, but I don’t really hear it .
Well, the whole point of my post was to say that actually, you do have to do just that. Otherwise you end up with the following:
A: Rancid and Green Day are punks from California and they sing like California punks. That accent is not even remotely British.
B: That’s funny. I was a California punk. And they sound English to me.
I’m happy to hear everyone’s thoughts, but is this really helping to answer the question in the OP? Eventually you have to decide what it is exactly that makes you think a line from a song is being sung in a particular accent, and then check to see if those features are not only present in the sung accent, but also uncommon in the spoken dialect of the singer.
-fh
Hazel-rah:
You’re right about the subjectivity of listener’s opinions on this. I guess we would need an actual linguist or something to make that determination. But those people’s opinions can be subjective, too, so where does it end? Myself, I think if it smells like s@# and looks like s@#, it’s very likely to be s@#$. 
Oh, and sorry I was curt in my original reply. I am a musician and songwriter, and sometimes I bristle at attempts to quantify or analyze these things…
Well at the risk of making An Arky all bristly, I’ll give you a quick example, hazel-ra (off the top of my head).
There is a Green Day lyric:
Do you have the time
To listen to me whine
…which to my ears is sung with an English accent. (In more or less the style of Joe Strummer.)
“time” comes out almost (but not quite) “toym”
“whine” comes out almost (but not quite “whoyne”
There’s something English about the pronunciations of “do” and “listen” in those verses as well.
Also from the same song, in a later verse, the word “control” gets a cockney pronunciation, with the ‘r’ in that word getting a pronunciation that is somewhere between ‘r’ and ‘w’.
From the same song (which, by the way, is “Basket Case” from the Dookie CD):
Sometimes I give myself the creeps
“sometimes” is almost “sometoymes”
“myself” is “mysewf”
and the ‘r’ in “creeps” is a cross between ‘r’ and ‘w’
It’s obvious that these guys cut their teeth on The Clash, because their vocalizations are very close to those of Joe Strummer. Listen to a Clash album, then listen to a Green Day or Rancid album, and you’ll see what I mean.
As an English fan of Green Day, I have to say those lads sound American to me. They may be trying to sound English, but they fail.
Yeah, well, the Beatles version of “American” is flawed as well.
I maintain that the Beatles (excepting Ringo) didn’t really attempt to sing “American” as such. They sang with the artificial “Mid-Atlantic” pronunciation, which is a compromise between British and American and sounds equally normal on either side of the Atlantic.
Artificial, because not native to any place. Not many people are born and raised in the middle of the ocean. 
But, on second thought, what does the accent spoken in Bermuda sound like? Bermuda is a British colony out in the Atlantic Ocean; the nearest mainland is North Carolina. Could it be the native land of the Mid-Atlantic accent?
Or equally abnormal perhaps? I suspect Ringo might have tried harder to disguise his accent because he had a stronger accent to begin with.
And that’s an interesting idea about the Bermudan accent being definitively mid-Atlantic, Jomo, but in fact it doesn’t sound like a cross between American and British as a R&R singer’s might - it sounds West Indian. And in case anyone is in doubt, that doesn’t mean punctuating every sentence with “mon”.
when did Ringo hide his accent?
He sounded as scouse as could be on “Octopus’ garden”.
on mid-atlantic: That is not to be confused with the american “mid-atlantic” region accent, which I found out about to my detriment recently
I think it has to do with the culture ofthe music. While the Beatles were trying to sound like American Rock and Roll bands, they just couldn’t pull it off. their “Yeah, Yeah Yeah”'s in “she loves you” are pure scouse.
Yes, you’re right about Ringo’s accent - I realised that after posting. Same story on Act Naturally, With A Little Help From My Friends and Yellow Submarine (a school bus favourite that one as I recall). He’s a bit more Californian when he speaks these days though.
Re: Green Day sounding “British”.
To me, they sound Northern Californian (And they are from Berkeley CA), as opposed to more mumbly Southern Californian.
It might be that they are somewhat British influenced, but IMHO it’s more a matter of musical style than pronounciation. Their musical style influences their delivery of the lyrics and probably also how (and when) the singer breathes while singing. That may have something to do with the “sound” referred to in the OP.
In this, I have to agree with Hazel-Rah; the core of the answer is in the comment:
"Britons and Americans sound similar when they sing because the prosody of singing masks features that distinguish the dialects from one another. Stress and intonation contribute to the character of dialects much more than people generally realize.
Of course there are different degrees of singing. Some vocalists basically talk over the music, others actually sing."
Yes, the observation that
Britons and Americans sound similar when they sing because the prosody of singing masks features that distinguish the dialects from one another
explains the phenomenon up to a point, but there are still plenty of examples of British singers deliberately attempting to sound like American ones (whether competantly or not). I’m less aware of Americans trying to sound British, but other posters have claimed that that is their impression at least.
Sorry, my writing was sloppy. I meant that Ringo was the only one who didn’t try very much to compromise his accent when he sang.
A thread that I started is still on the ‘front’ page even after over a week of me not venturing to the SDMB?
Should I be proud of that?
Probably not because it’s probably sheer fluke that I started a conversation that is worthwhile.
I’m off to check where all the other threads I started on the one day of excessive SDMB posting have ended up.
P.S. Isn’t it a bitch when you are typing away without realizing that the insert key had been inadvertantly pressed and all the text after what you are typing is disappearing.
P.P.S Back to the discussion guys…
A song that came to mind as I read this thread is “Wind-Up” on the Aqualung album by Jethro Tull (a very British group).
Singer Ian Anderson pronounces “half-assed” as if it were “hoff-assed.” The inconsistent pronunciation of the short “a” makes me laugh every time I hear that song. I suppose it would have been even funnier if he sang “half-ossed.”