Thank you, Ian, and you are quite correct ... apologies, I should have asked " ... in a Numbers table page or (using the correct terminology) sheet?"
And yes, as noted above, I could see the sheet headers and footers when I pressed 'print'. But it never occurred to me to actually try typing in that space ... duh ... which I have now just done and, of course, it works. Problem solved! But I have to say, that seems a most un-Apple way of handling things, hardly "intuitive", especially for those of us used to working primarily in Pages. And before turning to bother the Community, I really did try searching the web, using as detailed/simple questioning as possible without success ... the main problem being the difference between table headers and footers versus page (or sheet) headers and footers.
Anyway, Ian, thanks again for your time ... I knew it had to be simple, and it was ... sort of!
Nick