Hi Keebellah
Thank you for your considered reply.
I will check out the suggestions about turning auto calculation off; there could be something in that.
I don't believe it is a network issue as I understand the file has been used both in a network and standalone environments
and in each case the result is the same, ie some 90 seconds to save the file.

Thinking through the suggestions, I can also check to see that there are no autosave macros running (I don't believe there are but no harm to check)
and I can also disassemble a test copy of the file by deleting one worksheet at a time until I can identify which worksheet (if any) is causing
the problem, and subsequently removing parts of that sheet. I may ultimately discover that the file is simply corrupted - I have come across
this scenario before !

Thanks again, I will confirm what if anything works in due course.