The Weekend's Viewing: Birdsong, Sun, BBC1 Hugh's Three Hungry Boys, Sun, Channel 4

"This war provides daily lessons in the extraordinary simplicity of the human anatomy," says Stephen Wraysford, as he points out a detail on an écorché drawing in his dugout.

Stephen has good reason to know this is true, because he's just experienced an unusually vivid cut-away diagram of the contents of the human abdomen, after a soldier under his command had his stomach blown open by a German shell.

The soldier died in front of him and Stephen's reaction here may look a little clinical, even unfeeling, to us. We know, though, that there's more to him than that because, like the original novel, Abi Morgan's version of Birdsong began elsewhere, at a different time and a different world.

It's taken a while to bring this book to the screen (much longer than is consistent with its enormous popularity) and it is carried towards us now with a kind of sacramental care, a deference towards its subject – the piteous horrors of the First World War – mingling with a deference towards the novel's established status as a readers' favourite. At first, I thought that the processional grace of Philip Martin's camerawork was intended to build a contrast; that the long, gentle tracking shots in Amiens would be replaced by something more violent and fractured at the Front – Monet pastoral brutally replaced by Nevinson vorticism. But as it happens, all of Birdsong turns out to be quite stately in its pacing – this being one of television's favoured ways of showing that it is in earnest. It's hard to resist the rhetoric – slow means gravely serious – but you take a risk that your characters will appear a little anaesthetised and numb.

In the trenches, that makes sense, but, even so, Morgan's Stephen seems a much colder, harsher figure than Faulks's damaged lieutenant. When Jack Firebrace is called to the dugout for court martial, having been found asleep on sentry duty, Stephen toys with his terror, appearing to decide his fate on the turn of a playing card, which is the behaviour of a sociopath not a wounded hero (think of Goeth in Schindler's List, or Chigurh in No Country for Old Men). And Morgan's decision to reshape the architecture of the book also underestimates the virtues of Faulks's structure, I think. Where he breaks his narratives into substantial chunks, Morgan cuts between peace and war from the very start. This points up the parallels between the two main strands in the book – the sense that the subterranean working of desire eventually detonates a mine in the Azaire house too – but it does so at the cost of ripening tension.

One can imagine the thinking behind this concession to viewer impatience – oh, they'll never wait that long for the explosions – but granting it nevertheless detracts from the slow build towards eruption that the book achieves more than once. There's always somewhere to escape to, in short, in a story that is about more than one kind of inescapable situation. And once you have escaped you find that war and peace have the same processional texture. There are times when it works beautifully (this is a production that looks stunning) but also, perhaps, too many occasions when you feel as if a wreath is being laid in honour of the book, rather than it being returned to you in renewed form.

Hugh's Three Hungry Boys is an amiable affair in which three friends have set out to travel from Devon to Land's End in a converted milk float, living only by barter and foraging, and using only sustainable electricity to top up their battery. So far, they seem to be proving that it's perfectly possible, as long as you have the help of a team of researchers and the considerable inducement of an attendant television camera. It also helps if you're not above foraging in the bins of a national supermarket chain when the fish don't bite. Good news for times of austerity.