Fifteen-year-old HistoryExtra podcast at Immediate Media is on track to double revenue to more than £1m this year thanks to a huge boost to listenership and advertising as well as a new content paywall.

HistoryExtra, the podcast associated with the HistoryExtra website and BBC History magazine, hears from historians and academics in a long-form format. It also runs some multi-part narrative series on topics such as the Salem witch trials and the end of Roman Britain.

The podcast, which started monthly and now puts out six episodes per week, currently gets between 100,000 and 200,000 listeners per episode, with more than a million downloads a week and around five million a month. It has recently surpassed 150 million downloads in total since its 2007 launch.