Thanks Pwa. The weight did feel pretty balanced and I tried to keep the heavier stuff low in the panniers. A useful addition was one of those stretchy nets with five hooks spread over the rear load for holding the day's shopping bag in place. Along with the bungee straps, I also held the hawser for the lock and a third water bottle.
I'll have a look at the cassette wrench you recommend for next time. I did have a spare spoke with me held straight by the pump but couldn't fit it. Would I be right in saying that you can also buy flexible spokes that can be inserted into the hub without removing the freewheel and can then be tensioned ?
As for the rock - I only had to use one on a single occasion where I wild camped on fairly hard ground one night. The rest of time the ground was soft enough to simply push the pegs in. The hammer is probably still laying on a shelf in a car port for bike storage at the guest house where I left it on the third day!
I would also add a small roll of duct tape next time as well. I had already wound several turns around my pump for emergencies but used this up fixing a split tent frame section and in fixing my map case. When I went to buy a new roll , none of the garages had any and when I tried an agricultural machinery sales desk I was told it was 10 Euros a roll
! I passed on that and then found a Euro shop a couple of days later where that's all it cost.