Well done TR, I wondered who'd spot that one first! I suspect that you have solved the riddle and I have certainly learned something new, which may be more than one might say of the OP, who seems to have abandoned his own thread. Thank you!
Upon reflection, perhaps you are simply speculating, just like me? Having searched for an OR 22 that relates to nuclear weapon development I've drawn a blank. Wiki gives this list for Nuclear Weapon OR's that are all four figure groups anyway:-
https://en.wikipedia.org/wiki/List_o...uclear_weapons
Do you have a link for an appropriate OR 22? In any case, anything related to the Christmas Island Tests invariably got christened Grapple, per the Operation. Thus Grapple Hounds, the abandoned pet dogs left behind by withdrawn personnel that featured in the RN Daily Routine Orders when the base was left on a Care and Maintenance status. Hence, Grapple Hounds to be fed, Grapple Hounds to sea, etc, etc.