ok, thanks penguinator and David.
David, my original post line was perhaps unclear. "...but not trying a ".lesskey" options file in my directory."
that meant the "lesskey" file I did set up according to the "mans" didn't seem to work though I may have misunderstood the pages.
and anyway,using spacebar was ok for forward only-
However, bit of an "aaarrrgghh" moment
On rebooting I've found that using the 'f,b' keys now gives a page certainly with "man" and "less" which believe me didn't happen before, which leaves the shift-up/down.