Re: Pigeon Post
Sorry no one has picked up on this post earlier.
I have had a look at Stampmoguls post on Stampboards and I'm not totally sure what he is referring to.
Checking CPs catalogue (section VP) there is reference to two stamps issued for the Marotiri Copper mines. One is the 1/- red illustrated on the thread on Stampboards and the other is a 1/- green-blue Barrier Island stamp overprinted "MAROTIRI" Pigeongram in black. The stamp, as illustrated, looks to be the same size. The CP cat value (1999 revision) is $7000 and $10500 respectively for green-blue and red (used condition).
So in conclusion I am not aware of any other (larger) stamp. Have you tried e-mailing Stampmogul via the Stampboards site?