Al Gore's An Inconvenient Truth was, said Rich Hall, “a PowerPoint demonstration”. “This is film history.” Nor was he joking, although initially Saturday's How the West Was Lost looked as if it would be about the jokes. In a B&B in the Wild West theme town of Tombstone, Hall, all narrowed eyes, stubble and multi-gallon stetson, roughed up a young movie nerd who had irritated him by dismissing westerns as “empty elliptical cornball shit”. Cue clip of Morgan Freeman in Unforgiven teasing his young cohort about shooting a non-existent hawk out of the sky. “You were the kind of short-sighted twenty-something that Clint Eastwood was addressing in that film,” Hall said, before dumping him among the cacti.

But that was a skit. Hall was never less than witty, but in an epigrammatic Alexander Pope way rather than a comical stand-up Alexei Sayle way. For those who regard Hall, with his irritatingly high-pitched rasp, as a mediocre comedy panellist and second-ranking stand-up, this programme was a revelation. Hall produced the sprightliest 90 minutes of cultural criticism I have seen in years, with ideas bowling out at the rate of at least one a minute, and no concessions to his less intellectual viewers.

Here he is on Sam Peckinpah's Pat Garrett & Billy the Kid, which employed Bob Dylan as an actor and to provide the score: “Peckinpah used Dylan to create a self-distancing effect in the movie to show how the iconography of all the characters replaces any true function.” You don't get “iconography” on Newsnight Review. This was as far from a typical Channel 4 clip show as you could find. Indeed, Hall preferred to use movie trailers than excerpts to extract the essence of the films he was discussing.

Hall's defence of the western was twofold. You could not appreciate modern movies if you did not know that the westerns had been there first. Taxi Driver was doubly sourced to Shane (“You speaking to me?” asked Alan Ladd) and to The Searchers (John Wayne's racist, incestuous-minded antihero Ethan Edwards was, Hall claimed, a proto-Travis Bickle).

More crucially, you could not understand America if you did not see that the western's values of individualism and self-reliance informed the country still. The settlers were not obsessed with guns but with protection. Their descendants, he said neatly, “are happy because they own guns and it is important to keep them happy - because they own guns”.

Reading across all eras, Hall made brilliant links. A bar-room brawl in a western is a platonic ideal of the sort of altercation your local probably sees most Friday nights; Peckinpah transferred the same operatic approach to gun fights. In fact, he pointed out, the east had higher rates of violent death than the west, but the myth of gun law and the need for climactic massacre had become indelible. Ford tried to atone for the violence of his earlier movies in Cheyenne Autumn (1964), but his overriding political message was that violence and the suppression of violence were crucial to nation-building.

You can guess what thought flowed from that: “We are at war with Iraq because some sort of Bible-thumping, tongue-tied, pretzel-choking, f***wit of a President actually convinced enough people he was some sort of laconic, Gary Cooper hero come to bring justice against the evil folks.” By the end, the title How the West Was Lost had gained geopolitical meaning. “The western is like America itself. It endures, it no longer prevails.” I said this was a defence of the western. It was, artistically. In a court of morals, it was a coruscating case for the prosecution.

Earlier on Saturday, Doctor Who's retiring big chief, Russell T. Davies, decided to show us what he could do without special effects or chases but with sheet upon sheet of dialogue. It was a story of possession and featured something inside Lesley Sharp (one of his favourite actors) repeating what everyone else said. The episode was largely confined to the four walls of a planetary sight-seeing tour. Think Stagecoach and Huis Clos.

Humanity did not come out of it very well, although personally I could not blame his fellow passengers for turning on David Tennant's increasingly irritating (“I'm clever, I am!”) Doctor. Midnight felt too much of a writing exercise to be really scary, but once again it showed that even if it fails as often as it succeeds, this series is not afraid of variety. Like the passengers aboard the charabanc, Doctor Who is dead scared of repetition.

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