Moggy,
Brilliant piece of historical archaeology!!
BUT – see http://commons.wikimedia.org/wiki/File:Barrage_balloons_over_London_during_World_War_II.jpg.
These balloons are very different from the balloon(s) on LST 422. The “fins” on the ones in UK were inflatable (and as I remember them from WW2). The 422 “fins” seem rigid and non-inflatable. Were these balloons a later marque designed to reduce the amount of hydrogen used? (Production of hydrogen ‘in the field’ is a VERY DODGY business!!! – been there, done it!!!). Not much Mr Google can tell me about it (but I’ve only skimmed!).
HTH
Resmoroh