Producer Heather Challands said: "UNIT has long been a reliable, exciting and ever-evolving part of the world of Doctor Who. It's one of my favourite parts, showcasing the flaws and triumphs of human nature through iconic characters such as the Brigadier, Osgood, Harry Sullivan and Kate Stewart.

"I was thrilled by the opportunity to delve deeper into times when the TARDIS isn't around and the Doctor's friends simply have to do the best that they can against impossible odds. This new range is an anthology series, with each story standing alone, going from the 1970s right up to the 2020s, to see how much UNIT has changed in its long history.

"Hostile Universe features a close encounter with Daleks during The Stolen Earth, finds the Vlinx feeling a bit frosty, shows the toll UNIT takes on some of its soldiers, and answers the question of how Kate Stewart was spending her time after her house was blown up!"

Script editor Jonathan S Powell said: "I love UNIT, it's one of my favourite bits of Doctor Who - all those classic '70s adventures and the fact that it runs through the whole show from then to the present day. It's quite an exciting prospect to be able to showcase all of that in a single set, UNIT through the ages.

"I’m really proud of UNIT Eras. It's been one of the most difficult jobs that I've had with Big Finish, because each individual episode is a universe all of its own, and you want to do justice to an era, make it sound and feel right, as each will be someone's favourite era of UNIT."