Concept:
The Cabinet Mission of 1946 consisted of three British members sent to discuss India's constitutional future.
Step 1:Recall the members of the Cabinet Mission.}
Lord Pethick-Lawrence
Sir Stafford Cripps
A. V. Alexander
Step 2:Identify the incorrect option.
Campbell H. Johnson was not a member of the Cabinet Mission.
Final Answer:
\[
{\text{Campbell H. Johnson}}
\]