The actual Blue Danube warhead was proof-tested during Operation Buffalo in Autumn of 1956 at the Marcoo (surface) and Kite (air-drop) nuclear trials[1] at Maralinga, Australia, by a team of Australian, British and Canadian scientists.
Although there were many plans for versions with higher yields, some up to 40 kt, none were developed, largely because of the scarcity of fissile materials, and there is no evidence that any were seriously contemplated.
The first Blue Danube was delivered to stockpile at RAF Wittering in November 1953 although there were no aircraft equipped to carry it until the following year.
The Short Sperrin was also able to carry the Blue Danube and had been ordered as a fall-back option, in case the V-bomber projects proved unsuccessful.
[3] Major deficiencies with Blue Danube included the use of unreliable lead-acid accumulators to supply power to the firing circuits and radar altimeters.
[6] A replica Blue Danube bomb is displayed in the Gorse Industrial Estate (the former site of the RAF Barnham facilities) in Suffolk.