Brass plaques as ornaments for the harness of cart-horses were first made in the late 18th century; they became very popular in the 1850s, replacing an older style of adornment with ribbons, woollen fringes, and tooled leather. In some areas brasses were still in normal use in the 1920s, and can still be seen at horse-shows and parades (Brears, 1981).
The oldest examples are also the simplest, and seem to be rural imitations of the silver heraldic badges worn by the carriage-horses of the gentry. A wide range of designs soon appeared, some figurative and some geometric; they included crescents and suns, which might be interpreted as lucky symbols, and the horseshoe, an undoubted charm. It is doubtful whether there was deliberate magical intent, since there was apparently no previous English tradition of metal charms on horses. In a general sense, however, anything shiny and eye-catching can protect against the evil eye and witchcraft. Popular writers have latched on to this possibility, creating a feedback which confuses the issue. Nowadays, some country people say horse brasses are merely ornaments, while others say: ‘The reason that metal was put onto the horse's straps was to protect the horse from bad influences; iron was thought to be a good metal for the job’; or, ‘you put…the head piece to protect their head and the breast piece to keep away evil spirits from their heart’; or, ‘horses wore metal on their head and heart to stop witches putting a spell on them’ (Sutton, 1997: 36).