Well I finally found out what the tape play organ is.
It turns out it's a Mellotron M400 painted red and not very neatly!
The front panel doesn't remove, and it looks like the lid has been replaced.
So let's say it's in average condition. But the motor turns over, and one really good thing ---there's an SMS2 in there which saves money on CMC-10 replacement.
The pitch knob seems disconnected from the motor though. It doesn't seem to have an effect. The serial number looks to be 1253.
It's for sale, so anyone wanting a Mellotron please get in touch.
I'll be happy to send pics / answer more questions for anyone interested.
Chris