THE greatest initial mystery about Father Brown, BBC1's much-trailed new series of adaptations of G. K. Chesterton's detective stories, was: why they were broadcasting it at 2.10 on Monday afternoons? This problem was cleared up in about five minutes: it is so God-awful that, while keeping faith with the time and money spent on producing it, they hoped to screen it at a time when no one would actually watch it.

Chesterton created a contrast to the standard detective novel, largely deriving from his sense of how different Roman Catholicism is (or was then) from the genteel C of E world. His Father Brown has a far clearer view of the power of evil, is unsurprised by the depths of human depravity, and has practical sacramental means to redeem them.

Chesterton's tales are also essentially modern urban or suburban, eschewing the nostalgia of much of the genre. So what does the BBC do? It transports the action to a chocolate-box Cotswold village peopled by toffs and comic rural types, updates it to the post-war era, and introduces manners, diction, and themes that are entirely foreign to the original.

Mark Williams is excellently cast in the title role, but his talent is completely wasted. Even basic comprehension of Chesterton's distinctions is lacking: in this showing, RC priest and fratricidal Anglican vicar are essentially interchangeable, performing a sentimental double-act that the author would have abhorred.

There are two kinds of church: those that permit, and those that forbid, the singing of "Jerusalem". Whichever camp you belong to, much can be gleaned about the origins of our dark satanic mills from Why the Industrial Revolution Happened Here (BBC2, Mondays). Professor Jeremy Blake offers a whiggish and anti-clerical account, citing Continental Europe's censoring church allied to a reactionary aristocracy as the reason why it lagged so far behind our island paradise of democracy, equality, and accessible coal.

I thought that nowadays historians acknowledged a more complex picture: many Abbés and the odd Monsieur le Comte were at the forefront of experimentation; much British innovation languished through vested interests. But, besides celebrating the triumphs of steam power and industrialisation, Blake revealed its shameful hinterland: the financial capital that made these possible was based entirely on our wholesale embrace of slavery.

Liberty and repression were themes of Ken Follett's Journey into the Dark Ages (More 4, Saturday). This is a kind of spin-off to the serialisation of Follett's novel set in medieval England, World Without End (Channel 4, Saturdays). Our author was keen to show, with short accounts of Hildegarde of Bingen, Marguerite Porete, and Joan of Arc, that women in the Middle Ages were not the anonymous ciphers of popular imagination.

Unfortunately, his excellent purpose was undermined by the re- enactments, and it seemed at least questionable whether he considers their consuming Christian faith to be focused on anything real. If not, then their achievements and sufferings are surely worth nothing.