DH.9 C1231 accident Turnberrry 5 June 1918, cause?

[Marian2]

Hugh William Elliott and Richard Brumback Reed were killed on June 5, 1918, when their DH.9 C1231 experienced a catastrophic failure and dove into the sea off the coast near Turnberry.

I am puzzled by two authoritative reports on the cause of the failure, which seem to me to be at odds.  

Lionel W. B. Rees, Commandant at No. 1 Fighting School at Turnberry/Ayr, sent a long and detailed letter to Reed’s parents, which reads in part: “the propeller of the machine exploded and disintegrated thus causing a sudden and overpowering strain to be put upon the engine from the violent increase in the number of revolutions per minute.  This would unseat the engine from its bearers and partially wreck it whilst still aloft.  This spin into which the machine got would throw a too strong strain upon the wing which was seen to fold, and there would then be no hope of a safe descent being effected.”  Rees makes clear that his description is based on the results of the Court of Inquiry that was held on June 8, 1918.  (I've attached a jpg of the newspaper article with Rees's letter.)

The brief summary from the Court of Inquiry, pasted to the backs of Elliott’s and Reed’s casualty cards, reads:  “The Cause of the Accident was in our opinion due to parts or a part of the fuselage breaking away and interfering with the working of the empennage, thus throwing the machine into an uncontrollable spinning nose-dive into the sea.”

Can anyone suggest why Rees’s account would differ from the C of I summary?  Would the full C of I report have offered several explanations and Rees favored one different from that offered by the brief summary?  Or is the C of I summary a much condensed version of Rees’s explanation?  
Or is there some other explanation?

Any suggestions or speculation from people who know a lot more about planes and WWI aviation than I do would be welcome.  I know there's no chance of figuring out "what really happened," but the discrepancy bothers me.