Just another manic Monday. Here’s the Bangles with a stripped down acoustic version. Forget the pixellated pictures, concentrate on the sound. It shows the sublime structure at the heart of the song, and is a timely reminder of just how bloody good Prince was in writing songs for women*.

But what makes “Manic Monday” work? What makes it such an unmistakeable Prince song?

Why is it so essentially Prince, besides…

(a) the infectious chorus with its clever counterpoint harmonies

(b) a clever shift in tone in the middle eight that the Bangles truly make their own (try googling the initial demo of Prince’s song two years before by Apollonia 6)

(c) the lyrics – where all the argie-bargies of the dastardly Working Week invade a perfect dream about a perfectly sexy star of the silent screen (Rudolph Valentino), and now our singing chief protagonist wishes it were Sunday instead (“that’s my fun day / My I-don’t-have-to-run day”), and in the middle eight she asks her lover “Doesn’t it matter that I have to feed the both of us, employment’s down?”, and

(d) that “frilly” keyboard riff – frilly in the brilliant Abbaesque sense – before the start of each verse?

I reckon it’s…

(e) what happens at the very end of the “frilly” keyboard riff.

Bear with me a minute (or do I mean a minuet?). I can’t explain it in crotchets and quavers because I gave up the piano – and the piano gave up me – after the set pieces of Grade 3. Long story.

And while I do have a couple of friends who are semi-pro jazz musicians, they speak a language that – like the very music that it’s supposed to illustrate – seems to come from an alien planet. I’ll try instead to grapple with what is happening at that precise moment in the song in terms of the absolutely basic pop mechanics that I can understand. If someone else can explain it better please do.

The Bangles version here is in D major. Yet the penultimate note of the “frilly” riff, the note that you notice the most as it lingers in the air is just one step or semitone below a D. It’s a C sharp (or is it a D flat? Whatever).

This does something magical. It turns the D major into D major 7.

Unlike a dominant seventh, which you get all over the place in rock and blues and R n B, a major seventh is more like something from jazz territory, or soul (Marvin Gaye’s “What’s Going On” is a fine example). But what does the major seventh do in this particular poptastic context?

Sometimes a major seventh’s effect can seem “heavenly” (Chrissie Hynde has a particular fondness for them – check out the angelic vocal harmonies at the very end of “Back on the Chain Gang”). Here, though, this C sharp just below (rather than at the very top of) the main D chord seems to have the effect of putting the song at the edge of, um, a very steep slope, down which it is about to slide. What it will slide into is never quite clear though – perhaps a deep sad pool called B minor – because in the end it never happens, and things go back to a “proper” D chord again.

The major seventh doesn’t quite supply the distinct tension of a suspended (“sus”) chord – one of those chords where you’re not sure if you’re in a major or minor key. The major seventh is a little more subtle than that. The added C sharp below the D is pure Prince, and is what makes “Manic Monday”.

It means that suddenly everything is just ever so slightly unresolved, uneasy, hanging in the air, about to slide, not quite sure of itself being a proper D major chord any more. In fact, it’s exactly like the start of the working week, when you’re “working for the man” in the late epoch of capitalist globalisation, oppression and ecological meltdown. Nice one, Prince.

(* Apart from that ever so contrived single with Sheena Easton)