Definitely of the same ilk, though Murphy's Law was more about circumstance and misfortune, and Orwell (esp. in context) is talking about misjudgment (lambasting the British government for not occupying Vichy French territories before the Germans, against treaty, exploited them -- Syria, in particular).
Thanks for the comment -- it reminded me that I did not include my #MurphysLaw tag. đ
Both this and Murphy's Law itself come from the WW2 era -- as does another relative, Heller's Catch-22. I wonder if there was something about that conflict, or that era, that gave rise to that sort of cynicism / pessimism (perhaps in reaction to WW1 not turning out to have been the War to End All Wars), or if there are predecessors that haven't gotten as much press.