Last Night's TV: The Curse of Steptoe, BBC4<br />Countdown to War, BBC2

"I wasted time and now doth time waste me," muttered Harry H Corbett early in The Curse of Steptoe. And he was not playing Harold – fantasising about thespian greatness from the clutter of the rag-and-bone yard – but Richard II. And his director, Joan Littlewood, was pleased. "That was a Richard for the masses you just gave," she told him, before suggesting that he'd soon be ready for "the Danish ditherer". Unfortunately, Corbett's career was just about to be ambushed by success, in a way that would eventually bring that Shakespearean line back to haunt him. In an office that Mussolini would have regarded as vulgarly ostentatious, a BBC commissioning editor urged the scriptwriters Galton and Simpson to give him "something gritty, something with balls", and what they come up with was "The Offer", a one-off episode for a series of comedy plays about the grating relationship between a Shepherd's Bush junkman and his son.

Galton and Simpson wanted to cast straight actors for their playlet, perhaps conscious that established comedians would have noticed that conventional punchlines were thin on the ground. And that fact proved crucial in getting Corbett on board, a rising theatrical star who was looking for scripts that had political bite. What he saw in "The Offer" was not the embryo of a light-entertainment hit but a slice of kitchen-sink realism shot through with existential doubt. "It's not a sitcom," he told his wife. "You haven't read it... it's practically Beckett." And the point of The Curse of Steptoe was that, by the end, it really was, the huge success of the series effectively trapping its stars alive, buried from the neck down in their own comic personas. Whether the curse here was comedy, rather than that old villain fame, is debatable, but there was no doubting that both Corbett and Wilfrid Brambell came to hate the roles that had made them rich and instantly recognisable.

Jason Isaacs played Corbett – "the British Marlon Brando" – and Phil Davis appeared as Brambell, two performers who were almost as much at odds in the rehearsal room as they were on screen. When he arrived for their first read-through, Corbett was already "off book" and in character, while Brambell, representative of an entirely different theatrical generation, grumbled about Method affectations and delivered his lines in cut-glass RP. And though Galton and Simpson had already embedded antagonism and mutual dependency into their script, the cruel genius of the series that followed was the almost vampiric way in which they moulded the comedy around the characters of their lead performers. Harold's poignant aspirations for a better life – his stumbling attempts at wine connoisseurship, his pretensions to intellectual superiority, his dreams of escape through acting – all had connections to Corbett's real life. And though Brambell was a lot further out of the closet than was implied here, the line that came to be associated with Albert – "You dirty old man" – must have felt peculiarly pointed when thrown back at him after his arrest for cottaging. Anyone who remembers David Barrie's Channel 4 documentary When Steptoe Met Son, broadcast in 2002, won't have found all this particularly revelatory, but Isaacs and Davis played it so well that it had a fresh life.

Countdown to War, Newsnight's series of short dramas marking the anniversary of the Iraq war, concluded with what was effectively a one-man show: Kenneth Branagh playing the role of Col Tim Collins, who gave a speech shortly before the invasion began that stirred the hearts of armchair warriors everywhere. Tuesday night's drama had covered the Parliamentary debate that endorsed British involvement in the invasion, following two Labour backbenchers as they agonised over which way to vote. It was a study of the collision of personal conscience with practical politics, with potential waverers being warned that they'd get regime change in Downing Street if they didn't vote for it in Baghdad.

Last night's film, by contrast, was about action, framing Collins's now-famous speech with vignettes from the last day before the war started. "You're all saved," he shouted as he walked into the staff officers' tent for his final briefing. "The paddies are here and this time we're on your side." In its published form, Collins's speech begins with the words "We are going into Iraq to liberate, not to conquer", but here Ronan Bennett had shown how it emerged from more mundane instructions about the pills the men had to take to counter biological weapons. "We are all taking more drugs than a scouser on leave," said Collins, a joke that wouldn't have enhanced his reputation for Shakespearean eloquence at the time, but helped preserve this reconstruction from misty-eyed hero worship. As for his closing line, "Let's bring everyone home and leave Iraq a better place for us having been there", it's hardly his fault that it now has a hollow ring.