So for lunch our lady friends actually left us and repaired to the pub up the hill. We found out the U.S. lost to Ghana. I tried to pretend to talk about football with the two hard men with the England flags. They indicated no optimism that they'll be done walking by the 3pm start of the England/Germany match, but they've brought a radio for just that exigency.

Finally, Tim and I pick ourselves up, gear up, and head out.

Borrowing another trope from previous walks, we agree the rest of today is definitely auto-settings day – no more shillyshallying around taking photos of flowers. This walk is going to demand our full attention. The second half starts with a hill:

When that pub appears, we both pause and regard it longingly. "Quite tempting," Tim says, and I laugh out loud. An afternoon in the pub sounds a lot more pleasant than another 13.1 miles.

There's also sheep shit on the hill, which "sheep shit and uphill" certainly calls to mind another walk, and so I hit Tim with a favourite sheep shit story. Tim loves it when I tell him stories from the Coast to Coast walk.

On the upside, Tim indicates he does feel somewhat rejuvenated after lunch – which was good because I don't think we'd have made it far otherwise.

We catch up Clare and Sarah, where they're camped out in a patch of grass. ("So this is where pirates eat.") Since we've generated forward momentum, Tim and I decide to carry on, confident the other two will catch us up soon. But, in fact, we didn't see them again until the very end of the walk – and then only Tim did because I was half-conscious in the back of the mini-bus.

We seem to be falling back into old patterns. While Tim relieves himself, I note that not only am I not crapping my way across Wiltshire – my half-healed colon has really gotten with the program – but I haven't even urinated once. I was sweating it all straight out. In the end, I wouldn't pee even once on the entire day – I'd even wake up the next morning and not have to pee. And this despite pounding litre after litre of water. This should give you some idea of the sun and the heat we were facing – and were about to start battling in earnest.

When I mention this to Tim, he starts admonishing me to drink more, and at shorter intervals. Good mate.

As you can see, we found ourselves on a tremendously long and straight stretch – but ullulating with hills – punctuated by red flags reminding us we were on a live artillery range. (Much of the walk was across military ground, otherwise closed to the walking public.)

We also get deep into one of our technosophical conversations, which is a great distraction from the pain.

That observation of course kills the conversation, so we walk in silence and pain – today's internal musical soundtrack provided by the wonderful Damone. Great hooks, great cadence. Get the Flash Player to see this player.

The second photo below shows me looking rather less happy. And the third photo illustrates why – we we basically completely exposed to the full summer sun out here.

As you will have no doubt noticed, I still haven't figured how to do video, and I haven't gotten any better on this walk. However, the one below actually is worth watching, as a record of our travails. Misery is certainly the best dramatic inspiration.

Somewhere along here we pass one of the event buses, parked out here presumably to keep an eye out for casualties. When I jokingly ask for a lift to the next checkpoint, the driver smiles and says, "Sure!" That's when I realise this is like special forces selection – you can quit anytime you like. Wouldn't you like to just quit? Make all the pain go away? A nice air-conditioned bus ride? Just ring the bell and it's all over.

By this point, my notes note, my feet are screaming – and even my back is complaining now. It's none too soon when we spot the delicious shade and water of the checkpoint oasis. The trouble is, it's only the Mile 17 checkpoint.