Unfortunately once history is deleted it is gone. It can't be undeleted once deleted.

WIth respect, your reply seems to be at odds with what I read on the internet where solutions are mooted involving for example the use of indexfile.dat readers and the use of various other types of proprietary software. Before risking these, I was wondering whether the use of a new Firefox profile might resolve the problem in a safer way, and one which had been successfully used by others within this support group

Hi Probationer, there's no convenient way to combine history from different places.sqlite database files. That said, you could try to extract an old file from a different restore point. In Windows 7, the "Previous Versions" tab is the easiest way to access those:

In your profile folder, right-click the current places.sqlite file, Properties, Previous Versions

Note: File sizes for database files are not very useful because the SQLite code preallocates space in chunks.

You can use the Copy... button to extract an old file, then use a third party utility to list out its contents: http://www.nirsoft.net/utils/mozilla_history_view.html

Note: that program is not officially endorsed by Mozilla, but it has been around for a long time.

If you don't find any older restore points, do you recall using the Refresh feature recently? That would have moved your Firefox profile folder to your desktop inside an Old Firefox Data folder. See anything like that?

Your suggestion worked very well and the utility functioned perfectly. Thank you very much for your assistance. Much appreciated.