It is mid-December, and when I leave home in the early morning there is not a hint of light in the sky. It is black and raw and cold. In the summer I would bike it but today I bundle up in a thick coat and get in the car, run the heater to defrost the windows and put on the headlights. Then off through the empty streets with their winking Christmas lights, up the hill past the trading estate and into the half-empty car-park.

I show my card at the desk, head down the corridor and the automatic door jerks benignly open, releasing a chemical whiff of chlorine. The fluorescent light hits me first between the eyes, and then the lovely blueness of the pool. I feel my spirits lift. Pool time. The alternative reality of light and warmth and water. Freedom.

This is the time of the Early Birds, the pre-dawn session from 6.15 to 09.00 a/m when there are no inflatables, flumes or swimming lessons, no aquafit, no schools, no private parties. The pool is for us, the Early Birds. Although we are a mixed gathering there is a camaraderie amongst us, largely unspoken, though we smile and greet each other at the showers or outside the changing rooms. We are more familiar with one another underwater as a pair of hairy legs in motion, or a stripey swimsuit, or an erratic crawl. It is often difficult to identify the underwater person with their dryside manifestation.

The pool is organised into sections for us. The Medium Lane and the Fast Lane are on the far side and take up a third of the pool. The rest of the pool is for all other swimmers of varying ability – the slow beginners who cling to the wall side, the ladies who swim a stately breast-stroke with their heads held stiffly upright to preserve their hairstyles, the older men with flailing backstrokes, the plump friends who chat as they swim slowly up and down the middle of the pool. Because it is unstructured, this section can be challenging. It requires alertness to the movement of others and tolerance of their differing speeds and styles. Sometimes a newcomer tries to deal with this by putting their head down and ignoring everyone else, smacking along with goggles on and head down so that others are forced to get out of their way. You can do it like that. But regular Early Birds co-operate.

After a period in the open section, I have graduated to the Medium Lane. There are pros and cons to lane swimming. It’s good for serious swimming. Early Birds here are committed to getting a quota of lengths done and there is no idle paddling about, or pausing for rests. It is however best suited to free-style, or crawl as we used to call it, where arms and legs are going straight forward in a narrow line. Breast-stroke is more challenging. I have long arms and legs, which span the lane when fully extended. They are not an asset. I have to pause myself in a straight line when passing so as not to kick my companions. Because you are swimming in a circle – up one side and down the other – it is also important to be going at roughly the same speed as other swimmers in the lane. If you are too slow you feel the gasping breath of another swimmer on your heels. If too fast, you have to tread water and be patient. But, one learns, there are conventions. You pull up at one end to allow a faster swimmer past. Even, if there are only two of you in the lane, you lift your goggles and interact to negotiate an up and down arrangement, taking a side each instead of circling. When all is harmoniously arranged all or both of you can settle into the rhythm of the swim, up and down the lengths, up and down, body easy, mind settling.

I often find myself swimming with another regular, a man who swims for an hour or more, always, like me, in the Medium Lane. We know each other well but wordlessly. We swim at much the same pace. Occasionally if we are paused at the same end we will nod or bid each other good morning before continuing. I am short-sighted and without my glasses I can’t see his face distinctly or his expression; I would not recognise him in the street. But we are water-intimates. I could pick out his leisurely rolling strokes from a pool full of swimmers. I know his stocky torso and his navy swimming trunks. I know he pauses slightly as we pass, just as I do. It is a cordial, co-operative relationship. When there are others in the lane we sometimes have to deal with less adjusted swimmers. I sense our mutual consciousness of them.

Sometimes, unpredictably, there are days when the pool is quiet and I can take a whole lane to myself. It is a special treat, to extend arms and legs luxuriously to fill the space from side to side, to be aware of nothing but blueness and body, free in the water. Is there some atavistic part of our nature that makes immersion so wondrous and so liberating? Some pre-human memory or the warm rocking fluid of the womb?

This place of paradise is a down at heel local authority pool where the tiles come loose from the bottom and the heating in the showers breaks down. They are going to build a new one, they tell us. But I am happy here. All the eastern side of the pool is glass, and if you are there towards the end of the Early Bird session you will see the sky redden and the winter sun rise over the traffic at the roundabout. School children hurry along the pavement in the dark, in the cold, while we look out from paradise. As the days grow longer and the sun rises earlier it lights up the water and we swim through sunshine.

What has this got to do with the Anglo-Saxons? Well, very little really. The Leisure Centre would be completely, utterly unimaginable to them. Perhaps that’s the point. If we look with Saxon eyes we can see the astounding reality of what appears to us as mundane and taken for granted. What a technological miracle it is, to contain a constantly warm lake of water within a transparent skin in the depths of winter. What an organisation of society that enables it to be open and available for every citizen for the payment of a pound or two. What a peaceable co-operation between strangers that lets men and women, young and old, share such a marvel together. Sometimes I am tempted to hanker after the natural simplicity of Saxon life. But today, in midwinter? Give me the swimming pool.