The letters TG on the neck are the initials of a Fender employee.
In an interview with Rolling Stone magazine in 1991, Clapton spoke of his friend Carl Radle: "..Carl was like my brother. He brought me out of my seclusion when I was taking heroin after the Dominos broke up. He stayed in touch and found Dick Sims and Jamie Oldaker and said this could be our new band. And it was. And then drugs got into that and booze and it created a monster again...It was all drug related. And within six months Carl was dead...Now I look at it all and see what a waste and what a great player he was and I'm sad. I mean, drugs have a lot to answer for in my life..."
The stage-shots illustrated show Clapton playing this guitar on two occasions:
a) At the KB Halle, Copenhagen, April 21, 1974
b) At the Garden Party IX Concert, The Crystal Palace Concert Bowl, London, July 31, 1976