For the sake of clarity, I want to explain why
(a) I think it makes sense to allow people to go out simply to be out, and not just to exercise, but
(b) the way this has been introduced and communicated risks turning a modest and sensible step into a calamity.

Most importantly, the epidemiology suggests that risks of infection outside are very low as long as people remain sensibly distanced and observe hygiene rules. So, sunbathing at a distance from others or sitting on a bench does not consitute a significant medical danger.

Conversely, it confers a number of other advantages.
First, there is a wide literature on the mental and physical health advantages of being outdoors, irrespective of exercise.
Second, those with gardens can already sunbathe. Allowing those without to sunbather improves equity.

Third, it is easier to enforce and avoids unhelpful arguments about whether someone is sitting down in the midst of exercise or just sitting down.
Fourth, it shows Governemnt is concerned with people's well-being and only imposing restrictions that are necessary to keep us safe.

So, overall, the benefits of change outweigh the costs - if, that is (and it is a very very big if) the change is not introduced in a way that undermines other crucial measures. So the way the policy is introduced - and the messaging - becomes ansolutely pivotal.

First, it is essential that there is preparation and planning: explaining to people why the change can be made, explaining why and under what conditions it serves the public good, explaining why it isn't an overall relaxation but a change of measures to combat COVID-18

Explaining why changing rules on going out require strengthening other rules - notably on distancing. None of this was done. The changes were briefed as freedom from lockdown. The end of the war. Anything goes. A recipe for mayhem.

Second, it is essential that there is clarity and consistency in the messaging. 'Stay at Home' demands a specific behaviour. It is clear what it means. 'Stay alert' is an abstraction. It isn't at all clear what behaviours it demands. But it gets worse...

'Stay alert' is then explained... as staying at home and working from home if possible. So what is it. Stay at home? Not stay at home? What has changed? Confusion abounds. Clarity, precision and consistency have all been lost.

Third, you need to prepare. If people are told they can go out more, you need to make it possible for them to do so without ending up in dense crowds. You need to make sufficient space available (once again - open the golf courses and playing fields!)