The duo star as Aziraphale (Sheen), a somewhat fussy angel, and Crowley (Tennant), described in the books as “An Angel who did not so much Fall as Saunter Vaguely Downwards,” and whose cosy lives on earth are due to be brought to an ungainly halt by the arrival of the apocalypse – due on Saturday, just before dinner.

The Four Horsemen of the Apocalypse are ready to ride, Atlantis has risen, and the Forces of Good and Evil are amassed, however plans for the Armageddon have spun wildly out of control and someone has lost the Antichrist. His name is Adam.

Actor Michael Sheen said, “To be part of the team entrusted with bringing it alive on screen is a bit of a dream come true to be honest.” “Bring on the apocalypse,” added Tennant.

Neil Gaiman – the writer behind Amazon’s recent hit American Gods – will act as writer and showrunner for the series which is based upon the internationally bestselling novel from Gaiman and the late Sir Terry Pratchett (Hogfather).

Gaiman said, “Terry and I wrote Good Omens (I like to think it's one of the funniest novels ever written about the end of the world and how we are all going to die) almost 30 years ago. It's strange that it feels more relevant now than it ever did before. I only wish that Terry could be here to see it come to life with such a fantastic team."

Pratchett died in 2015. His former assistant, Rob Wilkins, will executive produce the series, and added “I can say with absolute certainty that Terry would be utterly delighted with our Crowley and Aziraphale – both David and Michael were very much in his mind for the roles when we began developing this series for television all those years ago.”

This is just one of the Pratchett novels that is thought to be under development for the small screen, with others, including The Watch and Wee Free Men, thought to be in development.

Good Omens is due to hit screens in 2019 on BBC Two and Amazon.