Just as there is a heraldry of raddle by which every farm has its blazoning of red, blue, or black on shoulders, back, or rump of the sheep, so each owener has a distinctive mark punched in the ear of his lambs. It may be in the right ear, it may be in the left, it may be in both... One register that I saw showed over a thousand variations from a few simple brands. When we consider that it is possible with only two different marks to get fifteen different badges of owenership we see what an infinity there can be when the motifs are more varied.
From Coming Down the Wye by Robert Gibbings, a scanned copy is HERE.
Image re-drawn by M.G. Reed 2017, from original.