Terence and Larry, many thanks for you patience and forbearance.
I did read the helpful article that Terence referred to and clearly misread it. Indeed, choosing Original and Title does export the original as an identical image together with the title. But therein lies the rub. One must have developed from the very start a rigorous regime for naming titles. If, like me, you tend to have several Events for, say, a holiday - quite simply because you took some photos on Day One and uploaded them, then another set on Day Two and uploaded them, I would go to the Event for Day One, select all the photos there and simply give them the Title 'Paris holiday 2016', say, with the sequential flag set so that they were titled 'Paris holiday 2016 - 1' etc.
I would then usually select the Event for Day Two and do the same. This, of course, results in photos that effectively have the same filename when trying to export and, naturally, OSX complains. I realise that this is a deficiency in my way of working but while working within iPhoto this is not a problem. Only when one tries to export.
Leaving that aside, the whole business of exporting is not ideal compared to the automatic incremental backup to an external drive that something like SuperDuper or Carbon Copy Cloner provides.
I looked at a couple of plug-ins for Flickr. First up was Flickr Uploadr which frankly is a joke. Second and which I'll probably buy is Flickr Exporter from FatCat. That seems to do what it says on the tin. Any recommendations for others would be very welcome.
Perhaps I can set up a remote connection with someone remote from me with a Mac and we could reciprocate allowing each other to backup to a partition on each others Mac.
Or maybe find someone where I can stick a Mac Mini on their network and use that remotely.