When the Cadbury Spots and Stripes pins came out numbered CAD0003 and 4, it was obvious that CAD0002 was 'missing'. Jerry from Cadbury Spots & Stripes kindly posted on the blog comments that the pin was being issued internally following a colleague design competition.
Thanks to a reader, here is a picture of the pin.
The pin cleverly mixes the 2012 logo with the 'glass and a half' motif to form a very nice looking pin.
No word on issue size.