The Week In Radio: A passionate portrait of a true gospel great

Mahalia Jackson was a woman on fire," said Cerys Matthews in Conjuring Halie in that tremulous half-whisper of hers. "Her hair danced madly when she sang out in her rich contralto voice, and (she) moved her listeners to shout and cry."

Matthews was telling the story of the late singer and civil rights campaigner who took gospel music out of the church and into the wider world. The granddaughter of an African slave, Jackson was the anointed Queen of Gospel in the Forties and Fifties until her protégée Aretha Franklin stole her crown, and was a friend of Martin Luther King. She can be heard murmuring encouragement to King as she stood behind him during his famous "I have a dream" speech in 1963.

Matthews has carved something of a niche making classy documentaries on forgotten figures of Southern gospel and blues music, so much so that you wish Radio 4 would allow her to do it more often. Here, as with her shows on BBC6 Music, her wide-eyed reverence for her subject matter shone through as she sought out blues aficionados and former associates of Jackson's to help tell her extraordinary tale.

She revealed how Jackson was born into poverty but found success with "Move On Up a Little Higher", at which point she bought herself a Cadillac big enough to sleep in. This was less of an extravagance than a practical measure, since on tour it was hard to find a hotel that would allow a black woman through its doors. As Matthews told it, Jackson was gloriously stubborn, refusing to submit to the efforts of record execs to tone her down and mould her into a refined concert performer. Fearful of being fleeced by unscrupulous promoters, she was rumoured to carry a gun in her handbag and only accepted payment in cash.

There was no real thesis here beyond the celebration of a monumental talent in danger of slipping into obscurity. "If she didn't move you then you cannot be moved," observed Tom Jones, a sentiment that was confirmed by archive recordings of Jackson that stopped you in your tracks, and then made you go straight to YouTube to dig out more.

While Matthews offered a portrait of a gospel star of yesterday, Radio 3 was pontificating over the mechanics of portraiture. It was a theme that threaded its way throughout a whole day's programming on Monday without ever being intrusive. In The Essay, the artist Maggi Hambling reflected on a 1978 self-portrait that depicted her with three arms, half a face and assorted objects including a teapot, a clownfish and a snake swirling around her head. "It's a collection of moments," she reflected. "Moments of action, brought into one moment which is the painting." Hambling saw painting as a form of therapy though felt it wasn't for her to explain what was really going on in her work, noting: "I agree with Matisse who said that artists should have their tongues cut out for the amount of rot they talk about their work."

Martin Gayford talked with great humour and insight about having his portrait painted by his friend Lucian Freud, and his subsequent understanding that a good portrait is not a record of a person's appearance but a document of their personality. It was Gayford, rather than Freud who proposed the idea, so he only had himself to blame when he was subjected to a mind-numbing eight months of sittings, positioned at the same angle and wearing the same clothes. It was, he said, "somewhere between transcendental meditation and a visit to the barber."