and here was me thinking it was one of those ‘plane’ based answers again..
almost herculean numbers.. have a look at what was on google. - search for
hercules aircraft - 5th one down..

hercules aircraft.. and those numbers are almost what the answer was.. r7a9 = A79.. its almost right isn't it?
explosive mix - well when you see one of those aircraft coming towards you on a bombing run (dropping the explosives).. you tend to think “Aww Shi*”.. letters A-S.
A79A-S.. i'll get my coat..
well done VictorE and sammyc.. the cookies are real tasty.. :bowdown: