Some listeners will have had quite a shock first thing on Monday. Turning on at six to Classic FM they would have heard a familiar voice but not quite the one they expected. In yet another surprising turn of events, John Humphrys, the fox terrier of news broadcasting, has just completed a stint on Classic FM’s breakfast show, swapping Brexit for Beethoven and smooth radio for the ebullient hectoring of the Today programme.

‘No need to readjust your radio,’ laughed Humphrys just after seven, before introducing the next track, Shostakovich’s Jazz Suite. Humphrys actually sounded as if he was beginning to enjoy himself, reading out readers’ emails, introducing the School Run dedication slot (‘For Noah, off to primary school in Leicester’) and Noah’s Dad’s choice, Leroy Anderson’s ‘Plink, Plank, Plunk!’, before quoting from fulminating articles in the Daily Mail.

‘I’m struggling to think of a greater contrast with my old job,’ he said in the press release that announced his appointment as stand-in presenter for Tim Lihoreau on More Music Breakfast. There were a few fumbles and extra-long pauses, especially at first, as if Humphrys was getting used to an unfamiliar studio. (Was he operating the mixing desk, I wondered?) But as he revealed his special connection with Elgar’s Cello Concerto because his son, a cellist, played it at his solo debut (‘I’ve still got the bruises on my upper arms,’ he joked, having squeezed himself so tight in nervous tension), you could hear his voice expanding, his mood mellowing, the years of politics slipping away. Even the naff adverts for home boilers, life insurance and funeral directors didn’t seem to irritate him as they might once have done.

Back on 4, the journalist and China expert Isabel Hilton began a three-part series reviewing China’s rapid development since Deng Xiaoping began opening it up for business in 1976. What are President Xi Jinping’s ambitions? Will his keystone project, the Belt and Road Initiative (BRI), launched six years ago, benefit the poorer countries it claims to be supporting? Or are its priorities to secure China’s borders and its access to key natural resources such as oil and gas?

As Hilton and her guests reminded us in this critically important series, there are much bigger issues at play in the world than our own domestic and continental worries. President Jinping insists that the BRI’s purpose is to revive the old trade routes of the Silk Road and provide infrastructure and industrial development to the countries along its route. But as China and the World (produced by Simon Coates) revealed, there are already unfortunate, not to say disturbing, consequences of China’s attempt to show the world an alternative model of economic development. Take Sri Lanka, for example, where China led the investment for the building of a massive new port in what was once a fishing village destroyed in the 2004 tsunami. Malpractice and corruption meant that Sri Lanka could not pay back the loans it was given by China to build the port and it now has no ownership of a port in its own territory. Instead, Hilton revealed, the Chinese government has a 99-year lease.

This is the kind of intelligent, informative, purposeful broadcasting at which Radio 4 excels, which makes it all the more surprising that it should now be bringing podcasts like Tunnel 29 into the ‘live’ mainstream schedule (on this occasion the 15-minute post-lunch slot). This ten-part investigation by Helena Merriman into the story of an East German who late in 1961 escaped to the West only to spend the next few months digging a tunnel under the Wall to enable others to escape tells a good yarn but in such a tediously overdrawn way. The production is sleek but so overwrought with pompous Hollywood-style music, cliffhangers at the end of each 15-minute episode, and a sound-effects department working on overtime. When Joachim Rudolph first arrives in the West he is amazed to discover the taste of pineapple jam, eaten with toast, cue the crunching of toast. In the tunnel we hear the wind, the dripping water, the spooky sounds of East German soldiers above. The programme-makers are proud of the ‘immersive, cinematic sound design’, which is precisely what’s wrong with it. It was all too obvious.

Podcasts are as yet an emerging art form full of youthful enthusiasm and shockability. Maybe in time they will become less mannered, quieter, more reflective and, above all, shorter. Rudolph’s story is gripping but could have been told, documentary-style, in an hour at most.

There’s still time to catch Benjamin Appl’s short series for Radio 3, A Singer’s World (produced by Clive Portbury). Appl, the baritone and former New Generation Artist, argues persuasively and passionately for the updating of Lieder-singing to draw in a younger audience while playing performances by some of his favourite singers — Teresa Braganza, Elly Ameling, Kathleen Ferrier, Dietrich Fischer-Dieskau, Peter Pears. In three gentle, reflective, beautifully paced programmes, he also takes us inside the mind of a Lieder singer. ‘We have to stop to aim to be liked by everyone and to try to please everyone. We have to stay ourselves and present ourselves and our inner lives to the audience.’