Well, actually the first loaf (the lead weight) was indeed the wrong flour. I couldn't get the gluten to develop at all and then after baking I discovered a gaping hole inside where the CO2 bubbles had coalesced into a single large bubble. The second one I knocked back and gave a second rise to before cooking (which I hadn't on the first) and, although it was fairly consistent in its texture, it didn't rise very much.
At that point I conceded that, at about two years old, the flour was probably past it so I went to the local mill and bought another 5Kg bag. While I was there I asked them to look on their records to see when I had bought the last one. Oh dear, it was 4 years ago! No wonder it wouldn't work properly.
So, with the new flour I set about making the third and latest loaf. Now with the arthritis developing in my hands I can't knead the bread manually so I use a Kenwood Chef with the bread hook attachment. However, even with the new flour I didn't seem to be able to develop the gluten properly. There just wasn't enough bounce in the dough even after ages with the Chef. There came a point where I said Soddit and just tipped the dough into the bread tin. Into the preheated oven at Regulo 8 for 30 minutes and then tip the loaf out and give it another 10 minutes upside down.
Result: better but it still hadn't risen as much as it should. There's obviously something wrong with my method (lack of manual kneading perhaps) but I'm struggling to find out what.