The one and only Mr. Elvis Costello
It is named "Trigger af after Roy Rogers horse and is a Martin N-20 Classical guitar.
See more at: http://en.wikipedia.org/wiki/Willie_Nelson
where you also can see some great photos of a guitar that has been around so to say...
"By the Time I Get to Phoenix" is the title of a song written by Jimmy Webb.
Originally recorded by Johnny Rivers in 1965, it was made famous by American country music
singer Glen Campbell, appearing as the opening track on the latter's 1967 album of the same name