Last Night's TV - The Night Watch, BBC2; Imagine, BBC1

A grim tale that looked the part

If you go to a cinema midway through a film you watch the second half first, don't you, so you see how the characters end up in the story," explained Kay at the very beginning of The Night Watch. And until the next showing starts, she implied, you're left with a mystery: "What happened to turn them into the people they became? It's like a riddle we have to solve." In the case of Kay – both in the original novel and in Paula Milne's adaptation for BBC2 – the big mystery is what made her so miserable. Few people can do glum quite as well as Anna Maxwell Martin and from the very first frame here, when she was shown standing blankly at an upstairs window, like a haunting, it was clear that she hadn't had a very good war. It's 1947 and she's bold enough about her sexuality to stride through the streets in men's clothing, but the looks she gets suggests she's way ahead of her time. And there are other mysteries too. Why is Viv, who runs a dating agency with Helen, so grateful to Kay ("I'll never forget it... what you did for me") and what's the deal with Viv's brother Duncan, who's just come out of Wormwood Scrubs for doing something unmentionable?

Richard Laxton had a nice trick for the repeated flashbacks, which revealed some of the answers to those questions – a high-speed rewind that captured, in its impressionistic slither, something of the characters' helpless subjection to what had happened in their past, as if history was an icy slope down which they occasionally tumbled backwards. But there weren't immediate answers after the first fall – just a partial revelation of who has done what to whom. We had to slip further back still to find the full explanation for Kay's wretchedness (sexual betrayal and wartime trauma) and Viv's disenchantment with her current man (a ghastly illegal abortion, which she only survived because of Kay's quick-thinking and subterfuge).

It looked fine, which is to say it looked tired and grubby and exhausted, the war having leached colour out of the world and left everything battered. And most of the set-piece scenes honoured the book's candid grimness. I've seen lots of Blitz scenes before, with doughty emergency workers picking their way through the rubble and flames. But I can't recall seeing one strewn with body parts before: "We think now it was four kiddies," said an ARP warden as Kay pitched up at a bomb site. "More limbs than we can account for." And, after Viv found herself getting the wrong result from a 1940s predictor kit (uncontrollable vomiting into the nearest lav) and a disappointing result from the 1940s morning-after pill (a deliberate heavy fall down the nearest staircase), her abortion was almost as grim as the one in Waters's novel.

What was a slight problem was the compression. A story with at least four concurrent plotlines and a complicated structure had been shoehorned into less than 90 minutes of screen time, which is tight even by cinematic standards these days. Why not three hour-long episodes, given the following the original novel had and the quality of this cast? As it was, the emotion of the relationships was necessarily squeezed towards melodrama and the overlap between global and personal history couldn't help but look a little soapy at moments. "Did the earth move for you darling?" you imagined Julia asking Helen, after they'd first clinched mid-air raid. "Yes, darling – I think it must have been a thousand-pounder and it landed very close."

If you think feral journalists are only a recent problem, there was an ironic reminder at the beginning of Imagine's film about John Lennon in New York that they could be just as unendurable in the early Seventies. Exhausted by the venom of the British press, Lennon and Yoko effectively fled to New York as very rich, very famous refugees, holing up in Greenwich Village, where they found congenial company and a healing degree of local indifference. "I'm just known enough to keep my ego floating but unknown enough to get around, which is nice," said Lennon. Not that the relief lasted for long. Lennon's anti-war activism soon had the FBI on his tail and the government pressing for deportation; and his own blacker moods resulted in a long separation from Yoko.

Michael Epstein's film didn't really have a new story to tell, Lennon's last years having been comprehensively documented already. But it did have some new ways to tell it, and some fresh interviews and footage, including sound tapes of the famously chaotic recordings with Phil Spector. "You haven't been in tune all evening so why change!" Lennon bellows aggressively at one of his fellow musicians, in a session that sounded more like a pub brawl than a musical endeavour. Elton John appeared to recall the evening when Lennon joined him on stage at Madison Square Garden, earning himself a 10-minute standing ovation from a hysterical crowd. And there was a sweetly touching recording of the very young Sean Lennon stumbling his way through "With a Little Help from My Friends". "What's the song called?" shouts Yoko from the background. "Er... what's it called... I've forgotten what it's called," says John. Unlike The Night Watch, this tale played out in conventional chronology, though sadly we've all seen the film already and know what follows the happy ending that Lennon briefly contrived when he became a father and found a bit of the peace he'd been pleading for.