We live in an era where almost every legendary band that can re-form has re-formed, and where technology means not even death is a barrier to 2Pac or Roy Orbison taking the stage once more. The artists who refuse to return carry a certain cachet, and Abba were the most famous hold-outs of all, which makes their decision to record new material a surprise, especially because they don’t need the money.

The first time around, Abba were not taken seriously as artists. The general critical consensus was summed up by a photo of legendary US rock writer Lester Bangs, wearing a T-shirt that read “Abba: the largest-selling group in the history of recorded music” and an expression on his face suggesting this was evidence of western civilisation’s imminent collapse.

In the years since they split up, however, their stock has rightly risen to a dizzying altitude. Björn Ulvaeus and Benny Andersson are regularly hailed as the greatest pop songwriting team of their era; the emotional depth and maturity of The Winner Takes It All – and indeed the personal psychodrama behind it – is pored over in a way it never was on release; their relatively overlooked final album, The Visitors, is acclaimed as a kind of Scandi-noir masterpiece. When the BBC made an Abba documentary a few years back, you got the feeling that rock critics and hip musicians alike were queuing up to sing their praises.

A burgeoning artistic reputation to match the skyscraping commercial success – you can imagine see why Abba might think twice about adding to their oeuvre. Then again, it’s not exactly a a flawless oeuvre. There was something fitting about the fact that their Swedish record label was called Polar: in their day, Abba strictly dealt either in pop perfection or records that made you want to rip your head off with embarrassment. The same album that contained Knowing Me, Knowing You, Money, Money, Money and the peerless Dancing Queen also featured the abysmal Dum Dum Diddle, a song about a woman who feels sexually threatened by her violinist partner’s instrument. “You are only smilin’,” she alleges suspiciously, “when you play that violin.” The same songwriter that crafted The Winner Takes It All also crafted Sitting in the Palmtree, a song about a man who deals with romantic rejection by sitting in a palm tree (“I will stay here among my coconuts”).

So if the new Abba songs are fantastic, there’s certainly a precedent. If they’re dreadful, well, there’s a precedent for that, too. Only if they’re mediocre will they come as a shock.