After having mapped about 100 of them in the last couple of days and having looked at many of them, I have taken the liberty of writing a wiki page for 'amenity=mounting_block' despite an already existing 'man_made=mounting_block' for #OpenStreetMap. Hopefully the images and statistics will speak for themselves.
https://wiki.openstreetmap.org/wiki/Tag:amenity%3Dmounting_block
#horsemapping #horses #opendata #heritage #heritagemapping