Hi as stated unisonic. Made as is, well constructed, biulder knew what they were doing.Does the name Peter Mattingley possible north London club or band leader ring any bells. I did see a resemblance of a group of six notes to a Jefferies duet system but only if you turned the layout through 90 degrees and mirror imaged it.!!!!He made a couple a year so there must be others. I have a maybe false memory of a post of a similar self biuld in a forum some time ago.
I have number the scale ,Pic right hand, starting C second row start down third row to D down fourth row up/ to E one button back F jump to top row G etc with numbers 1 -15 over the two octave progression finish 15 C end minus one second row if that helps.
kind regards