I have signals with either ink stamped or incised P within C. This is the first time I've seen anything marked "C.P." Does this pre-date the ink stamped P within C marking? About when would this marking have been used? Paul Axman provided me with the following information . . ."Hi Clint, The CP marking you have is not very common. I have it on multi's, and some uni's. I have the same signal as yours in light blue, I would suspect that mark is from the 20's. I have a multi with CP Co Ltd 1927, and there are some dated specimens from the early 30's that have the p inside the c mark. The earliest pieces have a mark like a cent sign. There were a variety of marks used, mostly on the multiparts" Thanks a bunch Paul!!!