It's very possible that H wanted a master volume, so they placed it behind the bridge. From what I've seen from bootlegs, he is using that pot as a volume control.
I'm not sure if that is necessarily a volume control. This video (around 0:28) seems relevant for the purpose of that pot. When switched at maximum level, it appears to activate the guitar tone, while when it is at minimum, the MIDI sound takes control.
As a note, my knowledge on MIDI stuff is close to zero, so the above might be non-sense.
It's the magnetic side master volume. Case solved. MIDI sound is always present, because H is standing on the Hold button on his Synth pedalboard.
So when H solos -> he hits a chord, steps on the Hold button on his synth pedaloard, opens the magnetic volume and solos over synth chord.
It looks like an early 80's 1962 reissue whith his standard setup. I think it was used sometimes during World Slavery Tour.
Then it's a 60-63 Strat. Thanks for the info.N
No, that is a real pre-cbs strat. The strat reissues in the 80’s had incorrect narrow spacing of the fret markets at the 12th fret. The guitar he is holding has the 12th fret markers properly lined up and centered under the A and B strings.
The narrow fret markets werenot corrected on the reissues until the late 90’s.
Please read the whole topic (I think I spoke about this guitar before). This is H's Florida strat. It was used during Running Free in 2011 there and resides in Nicko's house. When H jams with Nicko he uses this guitar (see Nicki's 6pth birthday jam).