en.wikipedia.org/wiki/Arthur_Tedder,_1st_Baron_Tedder

The sentence says Tedder’s department was transferred to the “newly created Ministry of Aircraft Production” at the outbreak of war in 1939. But the Ministry of Aircraft Production was not a 1939 body.

The UK National Archives’ research guide identifies the “Ministry of Aircraft Production, 1940-1945” and explains that the MAP “took over responsibility” from the Air Ministry. Because the ministry itself dates from 1940, Tedder’s department could not have been transferred to it at the outbreak of war in 1939.

So the claim is incorrect on timing: the transfer could only have happened after the MAP was created in 1940, not at the September 1939 outbreak of war.