By 1941 it was obvious to all that the arrangement was not working; Whittle was constantly frustrated by what he was seeing as Rover's inability to deliver production-quality parts for a test engine, and became increasingly vocal about his complaints.
I 1941 var det åbenlyst for alle at arrangementet ikke virkede; Whittle blev konstant frustreret overhvad han så som Rovers manglende evne til at levere dele i produktionskvalitet for en testmotor, og blev stadigt mere højrøstet med sin klage.