Cadbury actually class these products as Gluten-absent, a term that I've not come across until today. They also say on their website that "We cannot ever guarantee that any of our products are 100% free from such contaminant". Take from that what you will, I personally think it's a cop out but hey.
Here's what they list as Gluten-absent:
UPDATE 08/09/2014: A comment has been left on this post saying that "an allergen alert MAY CONTAIN GLUTEN on some of their products that used to be listed as gluten free by ingredients."
*I've checked the Cadbury gluten absent section of the website where this information originally came from and found two new items have been added. The seasonal items have been removed. No indication of any other changes but ALWAYS CHECK THE LABELS, just in case!