Another nine-hour day today here and we're both feeling pretty weary with a kind of deep tiredness that I've never experienced before. The photo (the 99th we've sent back from the tent) is of me in the standard pose I adopt if Tarka pauses while he's in the lead, perhaps to remove a layer of clothing or to double-check his bearing. With the ski poles in my armpits, my wrists dangling in the straps, my knees buckled together and my hips braced by the sledge harness, I can relax to the point of almost falling asleep.

As you can see, the blue skies we've been enjoying of late were replaced by a murky, flat grey today. We were both really lethargic getting going in the tent this morning, and both distinctly lacking in mojo for the first session of the day, which is often the hardest mentally as it entails exchanging a warm, comfy sleeping bag for nine hours of hard work and drudgery in a harness and, in today's case, what might as well have been a grey blindfold.

I find it interesting how little Scott talks about his physical and mental condition - and the daily battle with fatigue they must have been waging - in his diary. On their January 10th, still en route to the Pole after leaving their final depot, all he says about it is that "The work was distressingly hard", and while I know more than most what he's talking about, part of me would love to have heard more about what it actually felt like for them, rather than which way the wind was blowing, or how many hours they travelled for before stopping for lunch and to make tea (for of course they didn't have the vacuum flasks that keep our drinks hot all day).

I'm going to sign off now as I'm on cooking duty and we're having a blow-out double dinner this evening with some of the leftovers from our resupply, in a bid to refill our fuel tanks for the last three days on the plateau. It'll be my brother's birthday by the time this gets published, so I'm sending many happy returns from 86 degrees south to you, Steve. I love you bro.