The book Laurie Lee wrote – As I Walked Out One Midsummer Morning – is my favourite travel book of all time.

A 16-foot canoe loaded with food, 500 miles of wilderness ahead of us, camping on islands under the stars: paddling down the Yukon River remains one of my favourite adventures.

I spent six weeks in the Canadian Arctic on an Ice Base on the frozen Arctic Ocean at 78 degrees north (at the spot often referred to in polar races as ‘The North Pole’, though in fact it was the 1996 location of the magnetic North Pole).

My head is thumping. My eyes are stinging. I’m weak with thirst.