Thanks a mil for the responses. I reckon I will go back to the shop tomorrow and ask another guy. In the meantime I tried to open it and look for myself
http://imgur.com/a/AVajE. But I cant get that metal ring on the outside off. I'm guessing if its like a normal bike do I use a hammer and screwdriver and knock it out from the opposite side? Unless its one of these so-called threaded bbs...
another query - if its not threaded and I buy the converter component, is there a danger that it wont fit anyway? Are bottom brackets varied sizes, esp old ones? I think mine is about 4-5cm diameter (cant say exactly as the crank arm is in the way.
I will let you know what the shop says...
Thanks again, always amazing help on this forum :-D