There are only two instances when it is acceptable to wear sunglasses: either because it is actually sunny - a moment of such rarity in Britain that I can remember more lunar eclipses than days of uninterrupted sunshine - or because one is hungover.
The second occurrence is a condition that many of us will be intimately acquainted with. It is when we feel so ashamed by an evening of bacchanalian prodigality that we cannot bear to look our beautiful world directly in the eye. It is the adult equivalent of a child keeping their head resolutely downcast as they receive a parental admonishment for raiding the cookie jar or for some other act of infantile rebellion. Such spineless behaviour should be viewed sympathetically. Let those who are without sin cast the first stone upon the unrighteous and, frankly, I try to be as far as possible from anyone who pretends to embody a modicum of virtue - they always seem so insufferably serious.
Where my clemency for sunglasses begins to wither however, is when artists, particularly singers, wear their ocular devices with a perpetuity that is offensive. No one is guiltier of this crime than the prophet Bono. His trademark Armani rimless lunettes not only make him look a deranged insect from Blade Runner, they also distance himself irrevocably from his audience. This is what I really detest about sunglasses. When I perform I want people to be able to look at the whites of my eyes. I want to dismantle the barriers between myself and the crowd, whether physical or metaphorical, and shout into the faces of each individual spectator. Performance, at its best, should be like an intimate relationship.
I once asked a thespian friend of mine what it was like to play a character every night on stage. He answered that, when he felt he had truly perfected a role, he no longer believed he was wearing a mask. It is his assertion that the finest actors don't actually act at all. Thus, without wishing to delve too deeply into Jungian theory, it seems to me that the most compelling artists are those who are able to project their true selves through their 'persona'.
And yet, this ideal is unattainable to those who stubbornly insist on donning sunglasses everywhere. There is something decidedly shady - forgive the pun - about inexorably wearing sunglasses and I am always convinced that the wearer in question is engaged in skulduggery of the most depraved kind.
My grandmother always used to tell me that I should never trust someone with sunglasses. It was good advice when I was five years old and its good advice now! This is why politicians don't wear sunglasses. They want us - the voters - to believe, albeit momentarily, that they are sincere, affable chaps. I suspect that, had Ed Miliband been veiled behind a pair of tortoise-shell Wayfarers during his 'One Nation' speech at last week's Party Conference, he would have garnered a slightly less enthusiastic reception from the British press.
Since when, therefore, did sunglasses become as ubiquitous as guitars in the music industry? They inspire only duplicity and inauthenticity. In interviews, their use is just plain rude. I would like to launch a public charter to ban sunglasses from the stage altogether but, alas, I have no political clout whatsoever.
Perhaps this article will cause people to ring my doorbell tomorrow in protest of my polemic against their coveted eyewear. Please do. It will afford me the opportunity of rearranging my hair as I examine my reflection in an array of UV-protected lenses. However, unless your name is Ray Charles, I won't be inviting you inside for tea and crumpets.
The new single 'This Jumped-Up Boy in Livery' by Matthew's band Kites is now available for download on iTunes: http://bit.ly/Vyxovv