Fair enough in the sunshine – and sometimes even on the dazzling snow – we need sunglasses to cope with the glare. So I’m not making a stand against the wearing of sunglasses as such. On particularly sunny days you might forget to take them off until you’re inside wondering why the print you’re trying to read is so difficult to see.  Shopping can be one such example if you’re just browsing: on go the sunglasses as you leave, off they come again to read the price, out you go again but stay in the shadows until the glare from a window, or perhaps the snow, prompts you to put them on again. For those of us with prescription glasses that’s swapping the two pairs round all the time and fiddling with a glasses case and you run out of hands to carry the bag, sort the wallet etc. In the end you keep the sunglasses on pretty much all the time.

So I do understand why there are times when you end up wearing sunglasses after the sun has gone behind a cloud or when it is not strictly necessary. The trouble with other people wearing sunglasses is that it usually means you can’t see their eyes. So what? I’ll tell you what: the eyes give us a big clue as to what people are really thinking and feeling.

There’s the obvious stuff like tears that suggest that the person has been moved emotionally. Then there’s the red eyes that suggest that they have been crying very hard recently or simply are exhausted (perhaps from not sleeping well previously). The less obvious thing is that eyes can give us a clue as to whether a person is lying or not. You can smile with the mouth any time you like: it need not mean anything sinister to smile and not really mean it – you might just be trying to be polite and avoid giving offence, I understand that. But a genuine smile shows in the eyes – in fact a genuine smile may show up in the crinkling of the eyes even if the mouth is too preoccupied with eating or talking, for example. And if a person’s pupils dilate (or not) we might have an idea how interested they are in us and/or in what we are saying.

But if you are wearing sunglasses I can’t see your eyes and I lose vital information as to whether you are genuine or not. Some people seem to wear sunglasses regardless of how bright it is (and I’m not thinking of those with a medical condition here). It makes it difficult to know their true intentions. A security officer might wear them so that you can’t see where they are looking – a useful precaution I suppose – but it adds a layer of difficulty in communicating with them. How do you catch the eye of someone whose eyes you can’t see?

In a recent TV drama (The Hustle on BBC 1) all the characters put on sunglasses after the successful conclusion of their latest scam. It had the effect of rounding off that little incident nicely and portrayed the characters as fashionable citizens. It also covered their eyes, which, as I said, also hides their true intentions. If you know the programme you’ll also know that the main characters are criminal confidence tricksters who have a Robin Hood like appeal. The fact remains that they are criminals and the sunglasses neatly summed up the fact that they use deception as their main tool.

So a pair of sunglasses can also be a mask, a deceptive disguise used to hide the wearer’s true intentions. That is a kind of hypocrisy: you can hide behind your sunglasses and say one thing while knowing or believing another.

And who’s to know? That’s why I’m not comfortable with other people wearing sunglasses when it is not strictly necessary – but I must admit, the possibility of hiding in broad daylight has its attractions.