a marshall head, but what is that cabinet??? i first thought it was a vox maybe, but it seems a little too rectangular to me. also seems like maybe there’s a logo in the corner?? i think it’s a studio provided amp, and it’s the same one/same brand as the one jimmy is using. here’s the live video:
My guess is it's Marshall 215 of some sort. The trim on the front, and the shape and thickness of the front edges are pretty similar to this:
I believe it was an Arbiter or Simms-Watts, short-lived brands with ties to Sound City and Hiwatt… Voodoo Guitar: Oddball British Hi-Fi: Sound City & Simms-Watts Amps The earliest European/UK gigs were done with Vox gear left over from the Yardbirds, maybe even the bass on the first album(Page using a tiny Supro combo). The first US tour was primarily Rickenbacker Transonics, with occasional Arbiter, Sunn, and Ampeg in the mix, depending on the logistics. The Acoustic 360 came after that, when the money started rolling in.
W.E.M ( Watkins Electric Music ) was used by a lot of early top British bands early in their careers . The Who, Stones, Zep, Pink Floyd and Hendrix (while in the UK ).