I got this information from an English Website dicussing the history of camera, English products in particular. Of course I wasn't smart enough to bookmark the page. But the referral to "full plate" was in direct reference to the introduction of the 15X12" camera in 1907 in England.

Found it

http://www.usinternet.com/users/rniederman/univ1.htm


"In 1907, Thornton Pickard listed the "New Model" in sizes from 1/4-plate to 15" X 12" and the original model in sizes from Postcard to 10" X 8". Apparently the original models offered were unsold remnant stock since they carried very low prices."