At Baglan playing fields on a fine summer's afternoon, the fence was photographed as it stood at the time with no interference from me.
The tree shots I took on this day tought me a lesson, "Do not use a polarising filter on a superwide angle lens (28mm and shorter) on 35mm film".
The reason for this is that a these filters will only darken the blue sky when the camera is directed at a certain angle away from the sun, a wide angle lens includes a considerable area of sky and includes the areas that don't polarize well, so you get a very uneven tone across the sky.
This is visible in this photo and in two others I will post shortly.