As you say Arthur brooch/badge 3 is definitely the Cornish Arms. I`d say it is the badge for the Royal Cornish Show as Camilla, DoC & Sophie CoW, have both been past Presidents & once they have been a President they are automatically made Vice Presidents. There are pictures of them both wearing what looks like the same badge. I just can`t find one close enough to read the words at the base. Prince Charles was once President & now is the Patron.