I think that the reason why I couldn't download this upgrade from Apple, is that I did not register the purchase or upgrade to Snow Leopard. Therefore, Apple didn't know about it. Does that make sense? FWIW I had a thorough search of this office earlier, and could not find Snow Leopard instal disks. Only Tiger. That makes me think I upgraded online? Not that it matters, much, now.
According to
this Apple document your iMac officially
vintage in the United States and Turkey and
Obsolete in the rest of the world so it would not be supported in Great Britain. However all MacOS updates since Snow Leopard (MacOS 10.6) have been free online upgrades and upgrade disks were available from Apple at a nominal cost (basically the cost of the media and postage). AFIK no registration was or is necessary other than a free Apple ID and Password in order to access the App Store. A DuckDuckGo search for obsolete Apple Software turned up sites such as
Macintosh Repository that offer old no longer supported Apple and Mac compatible software products and OS versions available fo downloading.
OK, Photos is not compatible with Mavericks, I checked that bit. I have to find some software which, when I plug in my camera, will upload the photos - just like iPhoto used to do!
Mavericks had a nice version of iPhoto bundled with it that should work on your iMac.
You can find a downloadable versions of iPhoto
here. I believe
iPhoto 9.4.3 would be the latest version compatible with your iMac and MacOS version. Hopefully that Apple link will work in 🇬🇧.
Actually you should be able to access the files in an attached camera or mounted SD card with Finder and simply drag and drop the file onto your iMac.
ps. We're heading out to celebrate our 40th anniversary!
May you all be as happy as we are when you are 20 years further along in marriage.
