The Cannabis Trade, Radio 4, 8pm

Can we still get a lid on cannabis after politicians took the controversial decision to reclassify the drug as a less harmful Class C offender? The short answer in this detailed two-part documentary seems to be no, and the implications are disturbing. Head teachers, among them Anthony Seldon of Wellington College, believes the drug is wrecking lives in boarding schools as well as in council estates, across classes and communities. Worse, most cannabis consumed in the UK is grown on our shores in an industry often controlled by Vietnamese cultivators. With the police on their tail in Derby and Liverpool, the programme takes us to the heart of this newly thriving business, in the process finding a child “gardener” – an exploited underage worker brought to England and living among hundreds of cannabis plants.

Tim Minchin’s Loving and Peaceful Yuletide Half Hour, Radio 2, 11.30pm

Nobody writes a comic ballad with quite the same verbal dexterity as the Aussie comic Tim Minchin, so thank goodness for a chance to celebrate Christmas with the writer-singer-comic and his band. This, remember, is the man who savaged New Age quackery with his hilarious If You Open Your Mind Too Much, Your Brain Will Drop Out, so expect heartwarmingly sarcastic fodder from this special selection of seasonally attuned material (though not all the numbers are directly festive) in a virtuosic show recorded at the BBC’s Radio Theatre with a live – and suitably giggly – audience.

Unnatural Death, BBC7, 9am & 8pm

The start of a new mystery for Lord Peter Wimsey, Dorothy L. Sayers’s dilettante detective, beginning with a nurse and an old lady. With Ian Carmichael.

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