If nobody is named as being responsible for something, then nobody can be blamed and punished. Also used more generally in favour of reticence on a subject.
Pack-drill
is a military punishment in which the offender is compelled to march up and down in full marching order.
1923
Peace in our Time
I
. ii.
Men had a way of omitting the names of those of whom they spoke; no names no pack-drill.
1925
Juno & Paycock
II
. 61
I know some as are as sweet as the blossoms that bloom in the May—oh, no names, no pack dhrill.
1955
Beckoning Lady
ii.
It just means no name, no pack drill, and always speak well of them as has money to sue.
1979
Hooky & Villainous Chauffeur
x.
If you gave your word to a girl you'd stick to it. But there as plenty as don't… No names, no packdrill, as my old dad used to say.
speech and silence