After the first episode, looking at "showstoppers" garnered acclaim owing to Porter's passion and insight into the history of popular music, tonight he shifts his attention towards the art of crooning.

Charting this form of serenading as it has evolved from Bing Cosby and Nat King Cole all the way through to Roy Orbison and Lana Del Rey, Porter dissects each variation on the sound over the course of one hundred years. Interviewing artists such as Iggy Pop, Engelbert Humperdinck, Joshua Homme, Beck and George Benson, he reflects on how crooning was kickstarted by the arrival of the microphone and went from being a means of musical seduction into one of popular music's most widely embraced styles.

Part two of Gregory Porter's Popular Voices airs tonight on BBC 4 at 10pm, and to whet your appetite check out our recent interview with the singer as he discusses his latest album, Nat King Cole and Me here.

Watch a clip from last week's episode here: