I'm the guy Capo de Monti enquired for.
I appreciate all the replies.I have spoken to people in Vancouver where I first heard a busker playing one, but sadly when I went on the web all I could find was a mention of his memorial service, but I bought 2 music cassettes from him which I have recently had put on CD's...they're wonderful.I have emailed groups in the US, Ukraine and OZ. They all want to help but it seems to me the info I need is not written in English.
I have followed up all the suggestions on here, most helpful altho some I had already contacted.
My instrument has 61 strings. 12 wound phosphor bronze bass strings, 14 similar treble strings but thinner and 35 steel strings. It also had 7 levers on top edge, which when activated each has a mechanism which presses down on selected strings and raises the tone by a semi- tone. I've arranged to meet the guy in London next week and I hope he'll have time to explain it all to me.
Thanks again PSM