After buying a new ladder, I needed some brackets to get it off the floor and out of harms way, so I made up some brackets from 2×3″ and chipboard that I happened to have lying around.
Here they are complete, very simple design fixed with lots of wood glue and 42mm drywall screws. They are secured to the wall with 3 3″x10 screws each. They have and will hopefully continue to prove capable of supporting the 20kg ladder. To finish I wiped them over with a quick coat of danish oil. Job done.