Twenty Twelve, BBC4, Monday <br/>Leaving Amish Paradise, BBC2, Wednesday

On the face of it, the BBC's six-part mockumentary Twenty Twelve, about the preparations for the London Olympics, seems to have everything in place to be a comedy gold medal-winner.

It has the timing, beginning as it did the night before Lord Coe unveiled a gargantuan steel clock to count down the final 500 days until the Games. It has the cast, including a noble Hugh Bonneville as the team leader, seemingly in control while ineffectiveness exudes from his every pore; and a hyper-assertive Jessica Hynes as "head of brand", a PR whose verbal tics – "OK, so, OK, so ... erm, OK, cool ..." – are as on the money as her dependency on management-speak: "We want to ramp up interest by going viral and launching 2012 2.0".

It has the pedigree, too: its writer-director John Morton invented the mocku genre just over a decade ago with the smooth People Like Us.

And, 10 years ago, Twenty Twelve would have been quite something too. But in the interim we have become so accustomed to the bathetic device of a voiceover dampening expectations that it needs something more – something like a Malcolm Tucker or a David Brent. The acting is good, granted, but if Twenty Twelve's characters had found themselves in The Thick of It or The Office they would have been secondary to one of those monsters. The writing is passable, with the occasional gem – but is it any great source of mirth that a PR speaks gibberish, or that a "head of deliverance" finds it hard even to "deliver" on a romantic weekend away?

What's more, it is hard to avoid the suspicion that Twenty Twelve's drama will never quite match the absurdity of the real thing. Its premise – that the team is bumbling along in a typically British way – cannot hope to equal Boris Johnson's hilariously archaic declarations (such as that "wiff waff is coming home") or the fact that the countdown clock broke down 17 hours after its unveiling. That Coe himself turns up in episode two speaks volumes: this is sympathetic joshing rather than scabrous satire. All a bit too cosy to be a world-beater.

Another director revisiting an earlier success was Andrew Tait, as he returned to the life of Ephraim Stoltzfus two years after his excommunication from his native Amish community for challenging its beliefs. Tait's aim in Leaving Amish Paradise was to discover the extent to which the world had changed Stoltzfus's outlook. The answer: not a lot. He still believes the Lord will provide all he needs – and, astonishingly, the Lord appears to be complying so far, including giving him a roof over his head.

Tait's documentary revealed much about the Amish mentality through the difficulties Ephraim encounters – making the change from horse and trap to car, say, or home-schooling his children. And it was also quietly moving, notably at the death of the newborn of fellow excommunicants Jesse and Elsie. "It was God's will," Jesse intoned in a hushed voice, and it was hard not to be impressed (or just concerned) by that absolute faith.