Here's an advert for the "new" Vortexion EG/10 from Wireless World November 1947. This looks to have a smaller loudspeaker, probably 10 inch like the Dance Band amplifier advertised at the same time. My guess is that the EG/10 used a pair of CL33 in push-pull rather than the four CL33 in parallel push-pull of the EG/20 - but it's only an educated guess. Again I'd guess that the EG/20 was produced about the same time and few were made. No adverts for either amplifier appeared in Wireless World after November 1947.
Later there were other, far more popular, British guitar amplifiers, e.g. Vox. See also http://www.vintagehofner.co.uk/gallery/gallery3/selm.html
I suppose it could be hung on a wall. Like this http://www.beatlesource.com/savage/1963/63.03.25%20hoffman/63.03.25hoffman1.html
In the condition it was found in it made no sense to power up. Some folks will just apply power and see what happens, I often see items advertised on Ebay with a note that "all the valves light up". I'd be far more interested if the seller hadn't risked blowing it up taken a test meter and checked continuity of the transformer windings. I wonder what happens to the stuff that folks find and goes BANG! when they check to see it it "lights up"?
As with any amplifier or radio of this age what I expected to find was that most, perhaps all, of the capacitors had failed. Some large electrolytic capacitors have extraordinarily long lives, so I favour testing them and giving them a chance to "reform". With this amp I found that the two larger capacitors were good, but the dual electrolytic smoothing HT for the two EF40 had failed, perhaps due to heat from the metal rectifier.
Here are some photos taken after the defective capacitors and the heater dropper resistor had been replaced.