A necessity: My short wave radio. Tuning into the BBC is a useful way of finding out what's going on.

A luxury: A Walkman. When I was in Afghanistan, you could not take any western things in because of the Taliban. I really missed my tapes.

Mementoes: I've developed a sentimental attachment to my rucksack.

If only: I'd love a teleporter or a sleeping potion that would put me to sleep just before takeoff.