Ok, the Trem pedal is here and I've given it a quick road test. On Sunday I have the first rehearsal with the eighteen piece orchestra and choir so I'll try it in anger then.
Meanwhile according to bedroom testing I like it a lot. Simple controls - speed and depth on the "soft" setting and just speed on the " hard" setting. I think the soft setting is more usable - for me at any rate.
I got pretty close to the Trem sound on the you tube clip with a modest amount of tweaking and a bit of grit on the Blues Junior. Very warm too. Seems well made by the good folks in China, metal case and super bright blue light to indicate "on". Not sure what that will do to battery life. Doesn't seem to add any noise to the signal when it's off, at bedroom gain levels anyway.
So thanks to Knackereddad for both the recommendation and the kind offer of a loan!