Seeker_UK
Feelin' nearly faded as my jeans
I think the doctrine in the case of 'no R4' is the launch decision is left up to the Captain, it isn't an order more of an "have you seen On the Beach?".
"On the Beach" is a work of fiction from 60+ years ago.
This is what Wikipedia says about it: https://en.wikipedia.org/wiki/Letters_of_last_resort