BJ,
Yes, that's the multi-gang tuning capacitor/condenser fitted with the usual large pulley on its spindle around which is wound the dial cord. This model is fairly intricate in that department due to the flipdown lid. The tuning knob is located on the right-hand side of the cabinet (as viewed from the front).
John,
Nope, no holiday on Monday here. We had a "bank holiday" a couple of weeks ago. (You can tell it was a holiday -- It rained!)
Tex,
The plastic covered wooden cases were very popular here on radio equipment in the 1960s. One trade name was "Rexine." The best way I can describe it is that it's a sort of plasticized textile covering. Some old radios, tape recorders, etc. turn up on e-Bay from time to time, although in varying conditions.
I'm not familiar with the Modern Techniques name; I've had a quick look at some of my old reference books just in case, but I can't find anything listed under that name. My guess would be that it was a small independent manufacturer, possibly even just using somebody else's chassis.
The valve line-up you listed was a very common one for British tape recorders of the era. The ECC83 is an audio amplifier, the ECL82 and EL84 were used as audio output and bias oscillator (for recording) in various combinations. Some models used only one of these. The EZ80 is the rectifier.
The EM84 is a cathode-ray display, commonly called a "magic eye" indicator. These were used as tuning indicators on some radios and as level indicators on many domestic tape recorders. Some types were round displays, but the EM84 is just a small horizontal bar. If you look closely you'll see the section which would have been placed so that it was visible through the panel. Love that green glow!
A name I'm sure you'll be familiar with is Telefunken. I was given one of these old tape machines when I was a kid in the 1970s. It weighed a ton (or so it seemed to me at the time), but I spent many happy hours cleaning it up and using it.
