This Mk1 Terror Bass 500 is in excellent condition and has recently been checked over by JPF Amps, the official Orange repair folk; one of the smoothing caps had come loose and so it had the entire power board replaced. I'm pretty sure it's in as good working order as a Mk1 can be.
Extras: it has the original carry bag, with strap, though the pocket zip doesn't work any more. It comes in a tough plastic Stanley toolbox with fold-out handle which fits perfectly and makes a rather good flightcase. It also comes with a -30db inline attenuator in case you want to tame the DI out, though I've never had trouble.
Brilliant amp, puts a very grunty 500W into either 4 or 8 ohms and has bags of character.
Price £300 £270. Try-out and pickup preferred in London SE5 but shipping possible...