Last Night's TV: They've dished out enough punishment

City Of Vice, Channel 4; Life In Cold Blood, BBC1

Henry Fielding and his blind brother John took their leave of our screens last evening (it's catching, that elegant 18th-century way of talking), having at last secured, albeit by underhand means, the money from Parliament they required to establish a proper London police force. Thus, City of Vice came to an end, and I was not overly sorry to see it go, for, though admirable in so many ways, and based on exemplary research into real lives and events, it fell marginally, f rustratingly short of being a really crackerjack historical crime drama.

My review of the first episode said rather cruelly that it had all the tension of a boiled carrot. I wasn't thinking of an al dente carrot either, but of the kind of consistency my wife's late grandmother was seeking at a family dinner celebrating her 90th birthday, in a hotel in her native South Yorkshire, when she handed the bowl back to the waitress with the memorable instruction: "Them carrots need another 15 minutes, luv."

But it occurred to me, watching the final episode, that tension was not what City of Vice was about. It was principally a history lesson, and a useful counterblast to all those Jane Austen adaptations from which we draw our notion of pre-1850 London, as a metropolis where the great unwashed played a minor supporting role to genteel society folk. Clearly, it wasn't like that at all.

Moreover, City of Vice offered some striking parallels with our own differently benighted times. Last night, Fielding (the splendid Ian McDiarmid, whose voice should be declared a national monument) discovered that girls as young as seven were being offered to customers of one of London's leading brothels, a place on Pall Mall called the Temples of Venus, run by a Mrs Fawkland from behind a gravity-defying embonpoint. So Fielding went along to Mrs Fawkland posing as a paedophile, in a scenario little different from the kind of entrapment used by police officers these days. Even as a magistrate, however, his hands were tied (another service offered by Mrs Fawkland, as it happened), and he was able only to release a single child from prostitution.

Clearly, London needed formal policing, yet the view of the establishment in the early 1750s was that there was something suspiciously, grubbily Continental about the idea of a police force, the same as we feel nowadays about eating horsemeat. Thomas Pelham-Holles, the Duke of Newcastle and a future Whig Prime Minister, listened to Fielding's pleas for funding for his proposed Bow Street Runners, but rejected them until he was himself brutally assaulted by a pair of "shit-arse blackguards". That's another thing about the 1750s: politicians didn't pussyfoot around with the language. When our own dear Home Secretary declared that she didn't feel safe walking the streets of London at night, "shit-arse blackguards" was clearly the phrase she was looking for without quite daring to find it.

Anyway, in September 1753, Parliament duly granted £200 of the £500 Fielding had asked for. The Bow Street Runners were up and, indeed, running. And the Duke of Newcastle never found out that the blackguards who assaulted him had been in Fielding's pay.

Whether or not that particular detail was historically accurate, City of Vice was as engaging as a history lesson as it was insipid as a crime drama. Best of all, at least from where I was sitting, it stimulated interest in the life of Fielding, who previously I knew only as the author of Tom Jones. Yet his Wikipedia entry reveals that Fielding was heroic in all sorts of ways (not least for risking social censure by marrying his maid after getting her pregnant) and that as a magistrate he once issued a warrant for the arrest of Colley Cibber, the Poet Laureate, for "the murder of the English language". We could do with more of his sort in public life today.

Still, they didn't have Sir David Attenborough in 1753, which evens things up a little. His latest epic, Life in Cold Blood, has swiftly become unmissable telly in our house, and my only quibble is with the scheduling: 10pm is late for the nation's nine-year-old boys to stay up on a school night, yet how can anyone whose idea of fun is collecting frog spawn be permitted to miss it?

Last night we met the giant African bullfrog (as big as a football), the South American red-eyed tree frog and the Panamanian golden frog, as well as the rain frog that lives in the Australian desert sand and pops up only after a downpour, which means he gets out and about as much as the late Howard Hughes. The same cannot be said of Sir David and his team, yet if ever there were justification for a TV crew having a tyrannosaurus rex-sized carbon footprint, this series is it. And this series will not offer a more eloquent summary of Attenborough's genius than last night's footage of a family of earthworms; he makes us say "oooh" where once we said "ugggh".