IT felt like turning up to Sainsbury’s in a clown wig and red nose.

I wore a face mask for the first time last weekend, at the supermarket, and oh how they stared.

I assumed there would be plenty of us, shoppers dressed like extras from Holby City queuing for our bread and milk. But no. Most people were facially unencumbered, opting not to follow Nicola Sturgeon’s advice.

Stuck in the queue for 10 minutes, as the wifey with the crazy hair and conspicuous scarlet face mask (home-made by my sister), I felt like the meerkats must feel at Edinburgh Zoo.

I haven’t felt that self-conscious since the time aged 13 I admitted to the whole class I liked Chris de Burgh’s Lady in Red.

This tells us something, this reluctance to wear face masks. Adherence to social distancing advice has been widespread, but with her recommendation on face masks – advice that was reiterated more firmly yesterday – the First Minister has encountered the limit of Scots’ willingness to fall into line.

Masks are optional and there are various reasons why someone might not wear one, ranging from having asthma to social embarrassment to scepticism about their value. I’m a bit ambivalent about them myself. But their low take-up seems to hint that we the public are deciding for ourselves what advice we want to follow now that we understand the disease better and have some experience of social distancing.

That independent-mindedness round the edges doesn’t have to be a big problem provided there is broad compliance. If people adhere to the spirit of the rules while straying a little from the letter of them, they may not be posing a risk to anyone, for instance by sitting on an empty public lawn well away from passing pedestrians.

But we are at a pivotal moment in our collective campaign against the coronavirus, a moment of maximum jeopardy. Minor infringements round the edges might not be critical, but the two-metre social distancing rule is. In the absence of a vaccine or effective treatments for the disease, then alongside the test, trace and isolate strategy (now called Test and Protect in Scotland), that willingness to stay a safe distance from other folk is our main, humblingly low-tech defence against Covid-19.

Stay At Home has been the slogan so far; in future, it should be Stay Apart. That is how we will keep the disease under control while easing back into normal life.

If adherence to social distancing started to disintegrate amid a general relaxation of attitudes, then it would be a serious matter.

The trouble is, there are anecdotal signs this might be starting to happen already, with some people.

In city centres, where a fortnight ago walkers on narrow paths were hugging the walls in order to pass each other at a safe distance, it’s now quite common to see groups wandering along several abreast making no effort to shift for oncoming foot traffic. Folk are lounging on walls in places where passing pedestrians can’t shrink far enough away from them.

And as some people start to act as if social distancing itself can be relaxed, others feel even more vulnerable during their daily exercise.

There are signs, in fact, that we are gradually becoming two tribes: the Covid cautious and the Covid carefree. But the problem is that unless we are united we won’t avoid the iceberg ahead: a second wave of coronavirus.

A second wave in Europe is far from unlikely, according to Andrea Ammon, director of the European Centre for Disease Prevention and Control, the EU agency which advises governments on infection control. In European countries, between two and 14 per cent of the population have had the virus. This leaves it many millions of fresh targets if given half a chance. If there is a second wave, epidemiologists warn it could be worse than the first, especially if it hits in the winter when healthcare systems are also dealing with flu.

Dr Ammon stresses that a second wave is not inevitable if people stick to the rules on social distancing but also detects a “straining” against the restrictions.

Yesterday, Ms Sturgeon laid out her proposals to ease lockdown from next Thursday. The goodies are naturally being rationed and we’ll savour them all the more for it: the chance to meet people from different households outside at a safe distance, resume certain non-contact outdoor sports, and pick up takeaways from our favourite cafes and restaurants.

But the problem is that each time there is talk even of minor relaxations of the rules, people jump one step ahead.

She stressed yesterday that “the danger of a second wave later in the year is very real indeed” and pleaded with people to stick to the rules, explaining that “abiding by them is what makes it possible for us to think about relaxing them”.

But with the Scottish Government having published a four-phase plan for reopening the rest of the economy, the danger is that people assume the end is nigh.

There is a public hunger for progress back to normality, as shown by the fact 100,000 people tried to download the plan in the first minute after it was published yesterday.

And it makes for tantalising reading, like leafing through a holiday brochure or a Christmas gift catalogue. There’s the prospect, one day, during Phase Two, of visiting an outdoor market, sitting in a beer garden or driving off to the hills for a walk with friends. Schools are expected to reopen in early August which is listed under Phase Three; during that period the almost unimaginable treat of visiting a friend or relative at home could become reality. Weddings could take place with more than close family in attendance. In Phase Four, mass gatherings could resume.

This document will give many people hope – men, women and children struggling with loneliness and deteriorating mental health, business owners and their employees, and anyone and everyone who just plain misses their family and their mates.

But whether we ever get there will depend on the infection rate which in turn depends on keeping up social distancing. If we can Stay Apart, then we might just avoid that winter of discontent.

Our columns are a platform for writers to express their opinions. They do not necessarily represent the views of The Herald.

Read more: Covid has hit the UK’s reputation abroad but Scotland will be judged too