With the catenary due to be erected on my Greystones layout, the question of cleaning the rails arose. I found the solution [i hope] on Youtube. Basically by fixing a wooden block underneath a flat wagon that I found at the Bray Fair last Sunday. The block is easily demountable as the photo shows.
It depends for its function on the two flat head plaster board nails, glued to the block and then inserted into the retaining holes in the wagon.
Preliminary tests indicate more attention to the type of material for the block will be required, possible more weight on the wagon.