Walls are generally straight, they follow boundaries, and are made with a minimum of materials to save money and time. But sometimes they are bendy. I recall a few in isolated places that had trees planted in the bends. The walls were in an area where fields had lots of stones, so were a nuisance for ploughs. But I think they also worked as wind breaks for sapling trees, which when they grew provided wind protection in turn to the walls.
If anyone knows about wall building, feel free to correct me on this.
In Cardiff, I have spotted two walls which also deviate significantly from the straight and also have trees in their bends, but I am guessing this is more a vandal deterrent, or perhaps strengthens the walls in case a vehicle crashes into them.
This is near the centre of the city, along the front of the Territorial Army centre.
This is in a nearby park. It’s opposite a school so may provide seating for parents waiting to pick up their kids.