1978 Muson Synthesiser Toy Synth and Sequencer on eBay
A big thank you to Tom for emailing me about this, and for the record Tom, you're right, it is right up my street!
Here's the description on eBay:
Vintage Synthesiser toy from 1978 in good condition it appears to be working fine but the sequencer pegs require a bit of a wiggle.
Heres a few bits of info i found on line
"Incredible Machine. Far ahead of its time - a mini sequencer with endless possibilites. Kind of a ROLAND TB-303 but much cooler & cheaper. The coloured buttons can be used to change the melody and rhythm - each color has a different tune. You can also change the speed and pitch of the sequence with 2 sliders.
However, not going to cheap though. Follow the link to take a look on eBay.
1978 Muson Synthesiser Toy Synth and Sequencer