An interesting and very appealing livery button from the Victorian? period, belonging to the uniform of some unknown noble family I think. Having a crown, coronet and a crowned lion is very unusual as is the lion being pierced by an arrow, full of rich symbolism but about which I know nothing except it came from the same dig as the 93rd foot button which took place in Kent many years ago. perhaps someone up on heraldry can answer to what it relates, I did try to research it many years ago but without any success.
It could be an early militia button from an early unit, mid 18th century perhaps, though a noble family livery button is my best guess so far.