What gets confusing is that the Mdina Earthtones colourway was renamed Tortoiseshell at IoWSG.
Mdina Tortoiseshell doesn't have the bubbly yellow. IoWSG Tortoiseshell does, and it was made at IoWSG pretty much from the start.
Marc now has a globe, with coachbolt pontil mark and signed by MH, so the date of that is certainly well before '78.