Good Omens: An unholy alliance of good and evil navigate the end of days in this sci-fi budget buster

If the world was about to end, even the most angelic among us would struggle to turn down the offer of an afternoon holed up in Soho with a crate of Châteauneuf-du-Pape and David Tennant.

That’s how Michael Sheen’s character decides to see out Armageddon; with an apocalyptic Withnail and I worthy drinking session.

Here he plays the angel Aziraphale to Tennant’s Crowley (Satan’s henchman) and they make a charming odd couple.

Tennant is a swaggering rock-star incarnation of devilish force. He’s wiry in black skinny jeans and sunglasses, charging around in a vintage Bentley blasting out songs by Queen.

There’s something of Bill Nighy in Love Actually about him. Sheen is a lush who likes Glyndebourne and, Crowley teases, “fascinating little restaurants where they know you”. Tennant says they’ve never acted together before as directors find them interchangeable. But their chemistry is electric and makes for an entertaining romp.

This show has been a long time coming. Based on Terry Pratchett and Neil Gaiman’s 1990 novel, it’s a classic story of a baby being born — except the baby is the Antichrist — on Earth to engineer the End of Days. The authors struggled to dramatise Good Omens (perhaps because aspects of it are so off-the-wall imaginative) but in 2014, when Pratchett’s Alzheimer’s was getting worse, he asked Gaiman to try one more time.

I don’t usually watch sci-fi but this adaptation has such a strong cast I put aside my prejudices — I’d watch Frances McDormand, Jon Hamm and Doon Mackichan opening an envelope.

It is budget-busting TV, made by Amazon with seemingly no limits (it will be shown on the BBC eventually too). As a result it looks mega, with sweeping desert scenes, ancient temples and blazes of fire that look straight out of an advanced computer game.

The plot meanders, with the voiceover of McDormand as God to make sure we don’t feel lost. We begin in the Garden of Eden, with Crowley and Aziraphale providing painful bantering commentary as they watch Adam and Eve. Then we leap forward to a recognisable modernish time, when two very different women are giving birth. The wife of the US ambassador is in the back of an ambulance with her husband guiding her through contractions via video link (he doesn’t want to miss this bonding moment and can’t wait to devote his life to his new son, but first the President needs him).

Meanwhile, Deirdre from Oxfordshire’s pregnancy has given her a craving for an egg sandwich. The babies are born at a sinister nunnery and one is meant to be swapped for the Antichrist (Crowley delivers him, the harbinger of Hell, in a basket). But not everything goes according to plan, due to an unbelievable plot involving nuns and pink biscuits. You must suspend your cynicism.

There are sweet moments — including one of the boys growing up and wanting a dog called Dog — and brilliant but all too brief appearances from Hamm and Mackichan as Aziraphale’s colleagues. Occasionally it verges on being too knowing and arch, but Tennant and Sheen redeem it, the message of their alliance being that even those with as polar-opposite views as an angel and a devil can work together.

The plot fits into the trend for high-anxiety TV — the BBC’s future dystopia Years and Years has at least three national emergencies per episode (offset by a weekly group dance scene). Good Omens cuts straight to the chase — no minor disasters, it’s officially the end of the world. This is an imperfect apocalypse, but with flashes of brilliance.