Inevitably there will come a time when that person who was your best friend back home starts looking like a cross between the Whore of Babylon and Uncle Nev who tells the same bad jokes at every family gathering.

This is a natural reaction to an unnatural situation. Humans were not made to spend two thirds of their waking hours with one other person while traipsing around a strange city with all their worldly possessions strapped to their back. It's human hubris gone mad to think that we'd remain sane under such conditions.

That's why God invented the Walkman. Instead of wasting your time wondering if contract killers take traveller's cheques, pop on a tape on and tune out the irritations.

Other inventions that might help include an engrossing book, a travel diary or any electronic gizmo which requires your full attention. But more simple still is a day spent with Other People. At the very least it will give you both some breathing space and at best, there's nothing like the foibles and idiosyncrasies of others to make you realise that the devil you know isn't so bad after all.