Discussed at length on pg. 18 of the June 1978 issue of Beat Instrumental and listed among McPhee's equipment on the back cover of Back Against the Wall.

Beat Instrumental, June 1978, "Don't Mention the Gr**ndh*gs! says Tony 'T.S.' McPhee. Peter Douglas apologises" by Peter Douglas, pg. 18

In line with this begin-all-over-again approach Tony has ditched a lot of the equipment he accumulated with the old band through some remains. "I'm still using the EMS Hi-Fi, mainly because I use it as a power supply. Let me explain: when this band got together, I thought right — I still had the Laney cabinets and all that sort of stuff I used to use — you can't walk into a pub with that stuff. So I thought I'd look around for some smaller gear. I'd got a fifty watt Marshall, but I found that was too loud — I couldn't get it to scream without It deafening everybody. Anyway, I was round at a friend's house and he brought out this amplifier — it was an old Guild, circa 1960 I should think. He said it didn't seem to work, and I didn't have any tools with me at the time, so I couldn't look inside it.

He told me he'd had a bit of an accident with it — he'd plugged it in and smoke had poured out of the back. Apparently there was a fuse missing and they'd forgotten it was a 110 volt amplifier. It had never been changed from the American voltage. So I walked off with it, bought myself another transformer and a few resistors, stuck 'em all in, and it worked fine. It's the sort of amp where the inputs are marked 'organ' or 'accordian'!

"I took the speaker out, 'cause I blew it. Anyway, it was obviously quite low sensitivity, so I knew I'd have to have to put something in front of it to wind it up. Now for some time I'd been using a transmitter/receiver, and that boosts the signal up a bit, but with the receiver it was always awkward to know exactly where to stick it. So I stuck the receiver on the pole of the Hi-Fli and plugged it into the Hi-Fli using the power supply. And the Hi-Fli boosted the signal up a bit more so I can get a raw sound at quite a low volume. I just plug it in, turn it right up, and away it goes."

A more involved way of raunching up the sound of a guitar could hardly be devised. The obvious question was — why? What was wrong with getting one of the new amplifiers on the market that can deliver everything from a slight bite to a fuzzy buzz?

"Urm . . ." A pause. ". . because whenever I've gone out and got a new amplifier they've always been a disappointment after a while. The only amplifier that I really liked was one I built myself a long time ago. It was the only one that would do everything that I wanted it to, and some time ago I got hold of the parts again — and transformers for valve amps are pretty rare now. I've still got these parts at home, so I must make another one up. But in the meantime this Guild functions well. It's just the right sort of sound. I think it was intended to be about fifteen watts, but the transformer I put in it gave it a bit more H.T., so it'll probably go to about twenty, twenty-five. It's just got one very old 12" Jensen loudspeaker in it — which blew, but I had that rewound with a heavier coil. At the moment I'm running it into the speakers of the Marshall — just using the speakers of that, 'cause it's handy just to sit on the top."

Back Against the Wall back cover

Guild 20watt circa 1958

Although the model is not specified, it can be deduced. In the 1958 Guild catalog for the United Kindgom, the 66-J is the only one of the three amps listed that is rated at twenty watts. The 1960 Guild catalog further specifies that the 66-J has a "remote speaker jack" and that its twelve-inch speaker is by Jensen.

In this instagram post by Mark Neill, he mentions this amp is owned by Nick Waterhouse