Thanks, OzStargazer - yes, I think a trip to my nearest telescope shop is called for.
(This would be the first time in a long time for me that an internet search / forum has failed to bring up a straight answer to a tecehnical query!
)
I'm beginning to think it is more likely to be an EQ1 clone. I found an Orion instruction manual
http://www.telescope.com/assets/prod...9126_07-10.pdf that spells out that an EQ2 mount should already have a circular drive gear and clutch installed on the RA Drive Shaft. My mount doesn't have these, suggesting it is more lilkely to be an EQ1 or similar.