The 12 days of Christmas aren’t quite over yet — I found 12 pipers piping on my doorstep this morning — but the festive cheer has been banished by a feast of diet documentaries. OK, feast isn’t the right collective noun for slimming programmes but you can’t avoid them this week. Is it some act of penitence for such gorgefests as Jamie Oliver’s Italian road trip and Rick Stein’s French boat journey? But for most of us in need of shedding a few pounds the best way would surely be to have Derren Brown mess with our heads so we eat more sensibly.

Sadly, the only pounds he was interested in losing were in notes for Derren Brown: The Heist (Channel 4). Posing as a motivational speaker, Brown was using his awesome ability to lead and mislead the mind to convince a bunch of middle-management types to take part in the “armed robbery” of £100,000. After the expensive con that was Space Cadets (wouldn’t it be great if they had actually blasted the contestants into orbit and left them there?), this set-up for Channel 4’s latest exercise in duping people sounded positively thrifty but equally mean.

I’m always at a loss to describe Brown. Is he a magician, a con artist, a psychological illusionist, the spawn of Satan? He so freaks me out that I’m afraid that by watching him I’ll be left with the urge to tap-dance naked down the high street whenever someone utters the word “aardvark”.

Actually, it was his Russian roulette stunt in 2003 that made me lose a little interest in Brown’s act. Only a brain-spattering failure would have proved that he really wasn’t cheating so it felt like an elaborate set-up from the beginning.

That’s why my own powers of persuasion led me to the skulduggery of Rome (BBC Two).

Ciarán Hinds departed as Caesar without uttering “Et tu, Brute?” but in a frenzy of stab wounds that would keep the CSI team occupied for weeks. The earthy soldier Titus Pullo seemed to find some countryside peace but his by-the- book superior Vorenus was left shattered after the revelation of his son’s true parentage led to his wife’s suicide.

This series was always better at conjuring up slums, bordellos and bizarre pre-Christian rituals than characters. Last night, gladiatorial combat unfolded more like a street brawl, with gushing arteries, decapitations and severed limbs, in a pre-Colosseum “arena” that wasn’t much more than a patch of sand. The occasional attempts at history were usually too glib to be engrossing — all those tribunes, consuls and triumvirates blurred into one big laundry basket of togas.

Yet who would have guessed that dirty old Rome would make for such a nasty, naughty new soap, an addictive guilty pleasure. The Dynasty-like villainy of Atia, Caesar’s she-wolf niece, gave way to the more layered, venomous machinations of Servilia, Brutus’s mother, played with beautifully poised grace and cunning by Lindsay Duncan. And Kevin McKidd and Ray Stevenson as Vorenus and Pullo gradually overcame their Roman-era Odd Couple act to become a kind of Don Quixote and Sancho Panza, with vying tragic flaws and opposing philosophies of life.

The concluding double bill was preceded by a repeat of Colosseum: Rome’s Arena of Death. It showed how soap-opera personification often acts as the awkward lubricant for the gritty stuff of scholarship when it comes to dramatised documentary. Rome, by contrast, had finally managed to settle into the high-stakes, high-drama mode of palace, war-room and family intrigue that made I, Claudius such fun. This Rome was built in more than a day but less than ten weeks.

Already making a return visit was A Seaside Parish (BBC Two). Last time, the BBC happened to be filming the female vicar of Boscastle when the Cornish village was devastated by flash floods in 2004. What could have been yet another exercise in domestic cosiness for the director/producer Nigel Farrell turned into something far more dramatic. Last night we found out how the community, and in particular the Rev Christine Musser, was faring with many villagers having been underinsured and struggling to get ready for the tourist season.

All credit to the series for not endlessly replaying footage of the tumultuous muddy torrent that washed away cars and buildings. But though it was touching to see the optimism of the villagers and the tired looking but tireless vicar at work, one was still left with the impression that without this disaster the series would be like a postcard — a pretty scene without any drama. Thank goodness my own life is so much more exciting, especially when someone talks about aardvarks.

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