The white around the doorways was first painted during the World War Two, to make it easy for occupants of the Castle to find the entrances at night if the lights were off during a black out.
The white rectangles haven’t been particularly useful since the 1940s, but have been repainted as part of the maintenance work of the castle since then.
Why? Well, presumably somebody thought that since they were there, the paint shouldn’t be allowed to get shabby, and painted them even when they were no longer useful… and the practice continued… in general, the person with the paint pot follows what he sees.
A painted window?
One of the windows also has the white paint, despite the fact that it isn’t a doorway – why?
At some point, long after the original purpose of the white paint was forgotten, somebody must have mistakenly painted this window too….. and the tradition has continued.