It was a trifling sum, but I couldn't get it out of my head: 30p, less than the price of a chocolate bar or a can of fizzy drink. That's what a bullet costs – 30 pence for misery/freedom/security/death (delete as applicable).
The Lifecycle of a Bullet didn't quite live up to its billing – Caroline Wyatt, the BBC's defence correspondent, didn't follow one particular missile halfway round the world, which would have been neat but tough to pull off (I have visions of her extracting it with forceps from Taliban flesh). She kicked off with the bullets' manufacture, mostly using old batteries and roofing lead, on machines that spit out up to 6,000 an hour. Then it was on to the firing range where they're tested, then Warwickshire, where they're stored in Europe's biggest ammunition depot, and eventually to Helmand.
It would have been interesting to address the question of how so many guns and bullets end up in the wrong hands, though I guess that wasn't really in Wyatt's remit. There were some disturbing revelations, such as the fact that since the Second World War there's been only one calendar year, 1968, in which a British soldier hasn't died in action. Better keep those bullet machines ticking over.
Every day, Witness provides often oblique takes on world events. Tuesday's had the Icelandic policeman who looked after Bobby Fischer during his legendary confrontation with Boris Spassky at the Chess World Championship (Friday's was the 40th anniversary of the American's victory). Saemundur Palsson sounded like the kind of bloke nothing could rattle. Years after, when Fischer was in prison in Japan, Palsson bailed him out, and Fischer became an Icelandic citizen. Their relationship began when the policeman fixed the antenna in his hotel room, and fetched him suits for the big match. When Fischer had won, a ball loomed but Fischer couldn't dance. No problem: Palsson taught him to waltz.
While the final dragged on, Fischer effectively became a member of the Palsson family. And how had the policeman's wife reacted to having a basically bonkers chess genius in their midst? "She understood it had to be done," he summarised. "She was a good woman."