In the archive we have a small collection of letters from famous literary figures. This letter appears to have no link to the school, and its provenance is unknown. Perhaps it was donated to the school by a collector?
Dear Sir,
Many thanks for your interesting book of photographs of Defensive Steel work which I have examined and herewith return.
I have done what I could and as the War Office is taking the matter up, it has entirely passed out of my hands.
Yours truly
A. Conan Doyle
Writing a bit scrawly and not always clear, though very expressive ts and capital letters. Looks more like 1716 than 1916. Does not use commas. Abbreviates October to Octr. Interesting.