The reason for carrying some balloons is that beneath the ship was fixed the sonar set that was being fitted to Nuclear submarines (very large and gave us a draught of about 26 feet). After inflating the balloon with hydrogen it was attached to a submarine and floated into the air whilst the submarine submerged. The ships OOW could see the balloon and so could pass the range and bearing to the sonar trials team so as to give them some idea where their sonar set should be looking.
Shortly after Apollo 11 returned from the moon David was instructed to follow with Apollo 11.5. The first lieutenant lent him his 12 bore in case of problems. Actually it got us into trouble from Plymouth as putting paint on the balloon destroyed its airtightness and so we had effectively written off one of the last 15 barrage balloons held by the navy.
The Verulam photos with a balloon provides a very tenuous link with HMS FLYING FOX.
Did you know that at the end of WW1, HMS FLYING FOX was based at Queenstown (Cobh) and that Castletown – Bearhaven was a kite balloon station at Queenstown and between late July and early August 1918 supported operations on HMS FLYING FOX involving American lighter than air operations (LTAs) from NASs in Europe?