http://www.iwm.org.uk/collections/item/object/30075148
http://www.iwm.org.uk/collections/item/object/30075150
A rather useful pair of s/p cards for the badge for the amalgamated regt. Dating the s/p to 1929. The design had been used by the Fifth's officers previously.
Combined with this card:
http://www.iwm.org.uk/collections/item/object/30075117 which declares the 6th Dragoons badge as obsolete from Jan 29, it suggests that the first card is indeed the first one issued in 1929 and not a later card produced for re-sealing.
I would suggest that the amalgamated regts was one of the ones who kept separate sqn identities badged to the antecedent regts after 1922. The 15/19th also did this but the 13/18th did not: the adoption of a 'new' badge for the amalgamated regts seems to have been regtl practice rather than any policy.