In reply to The Ex-Engineer: Thanks for the suggestions guys. Just to clarify - I am not fussed about features (if it has em it does, if it doesn't it doesn't). What I am concerned with is the fit and rough capacity to suit my needs - I don't actually think that's too much to ask for in a rucksack!
I need to fit in: sleeping bag, stove/pan/gas cannister, trainers (I'm wearing walking boots), rock shoes, flip flops, basic clothing, enough warm clothes for a cold person in new zealand (admittedly in summer/autumn), waterproofs basic first aid kit, wash kit, hairbrush, camera lens, few misc bits and bobs.
I managed to just about squeeze that into my Macpac Pursuit leaving just my waterproof, SLR camera and day to day bits (passport, wallet, kindle etc) out for a day pack. But the sack was totally rammed, so no room (for example) to add anything extra I want to bring back from the trip, or to swop my walking boots for trainers when I'm out there. Plus to get unpack and repack would take rather a long time to complete the tetris model! Hence why I'm looking for something a little bigger.
If I left my rock shoes and camera behind then I may manage but I'd rather not. I'm planning to do some walking when I'm out there, hence needing the sleeping bag/stove/pan etc.