Pete, mickeg, many thanks for the advice - it's in a cool dark place in my wardrobe, but I unfolded it, so I better fold it back up!
Pete, on my recent ride from Auckland to Wellington, 99.9% of drivers were great, only one truck that passed frightenly close passing me on a narrow bridge with no shoulder, but that has been the one and only scary moment since I've been back riding for the last four months. I've been pleasantly surprised by the lack of any bad car driver behaviours - but it's early days for me, as only coming up to 4000kms on the Nomad.
Getting back to tyres, now that I've done a couple of tours, one of 9 days and one of 4 days, and now I know I can trust the bike and set up, I may very well carry a smaller, lighter back up tyre, as the Marathon Mondial 26 x 2.15 may have been a little bit of overkill as the spare, especially as it took up quite a bit of room in my pannier - but I'm learning as I go and I like to work these things out for myself.
Only one close call during 800km from Auckland to Wellington.
http://nztony.smugmug.com/Auckland-to-Wellington-March-2/