http://www.youtube.com/watch?v=6SgU1FgoQEs

Am I right in assuming that the verses are 3 bars of 4/4 and then a bar of 6/4? 

Can't quite wrap my head around the flow of this. 

Could be. Or 2 bars 4/4, 2 bars 5/4.

jamesg1213


Could be. Or 2 bars 4/4, 2 bars 5/4.

Hmm, technically yes, but I was using the bass line as a guide...

I'm just guessing. I can't really feel the '1' after the 2nd bar at all. 

It's definitely confusing. 

They seem to be doing it as a straight 12 bar shuffle here; http://www.youtube.com/watch?v=K0RXGDcXa0E

This is an example of simply keying on the singer and not worrying about cohesive bar structure.  You hear the same thing in old Bluegrass and Blues tunes all the time.  It's not that they simply add a 2/4 bar instead of a 4/4 bar at the same time every verse or chorus... it's that there really is no rhyme or reason other than when the singer decides to come back in.  Usually it's a single bar count that gets dropped making it, say, seven bars of 4 and one of...well...1.  Can be frustrating and downright corrrnnnnfusin.  But once you've had to back up a slew of "singers" who can't count it gets easy to "catch em".
 
 
PS: if you listen close you can hear the bass player move to the 4 chord incorrectly later in the tune throwing everybody off for about a nanosecond.

Wrt to the bass line, I am counting it more as 4 measures of 4/4 and a measure of 2/4 instead of counting that last measure as 6/4 … reason being, it just sounds like they stuck 2 extra notes in there to get the vocals to come around.  It’s not like a measure of 6/4 where they are completing a musical idea.

The vocals are arranged so they don’t step on each other.  The “call” picks up on beat 4 at the end of the intro and stops on beat 1 of measure 3.  The “response” (Buick 59, Buick 59) starts on beat 3 of measure 3 and stops on beat 1 of what would be measure 5.  From that point on, to keep the math correct and prevent the vocals from stepping on each other, that 5^th measure is a measure of 2/4 with the response stopping on beat 1 and the call picking up on beat 2.

It’s not random … an arranger sat down and did the math.

… just a drummers perspective.

No, it's not random...but no arranger sat down and did the math...that's just the way they did it...in rehearsal and in performance.  It's simply primitivism made manifest.  Rock on.

I think it's definitely planned. I understand when blues/folk performers add random beats here and there to fit the words, but that's more of a spontaneous thing which can change from performance to performance, and is usually when it's a solo performance. I do it myself when improvising solo fingerpicking pieces. However when you have a band cutting a track in the studio I'm pretty sure the structure was deliberate, even if the performances were flexible to some extent. 

I hear it a lot in traditional Irish tunes, especially when there's a vocal. However, when a band takes a traditional song and turns it into an arrangement for multiple musicians, they still sometimes throw those "random" extra beats in, only they're not so random. It's a way of giving an ensemble performance a more authentic, organic feeling. Take P Stands For Paddy as recorded by Planxty, plenty of extra beats thrown in, but it's obvious they've practiced the bejesus out of that arrangement. 

But it still throws me, and I have a hard time counting it, especially in a tune like this where the bass line is so familiar yet throws you that curve ball. I often wonder whether it sounds odd to me simply because I have a musical mind which looks out for this stuff, whereas if you never think about music theory, it mind sound totally natural. Another example is Blackwaterside by Bert Jansch, I transcribed it years ago and it took me ages to get my head around all the bars of different length. But I remember playing it for a non-musical friend and asked him whether he found anything weird about the rhythm...he said he didn't.