Donald McLachlan

Journalist and author of Room 39: A Study in Naval Intelligence (1968), the institutional history of the British Admiralty's Naval Intelligence Division that is the primary source behind John Godfrey's 1939 origination of the Admiralty Code's two-axis grading system.

He matters to this vault as the unread primary anchoring a load-bearing claim: the vault currently knows his account only secondhand, through Ludo Block's 2021 retelling, and Room 39 itself is access-restricted (controlled lending on archive.org) — the gap that question-verify-godfrey-nid-origin-against-mclachlan-room-39 exists to close.

References

• claim-godfrey-1939-devised-admiralty-codes-two-axis-grading-to-fix-report-anarchy — the claim resting on his account.

• observation-admiralty-code-diplomatics-independent-origin-not-shared-descent — the synthesis that also rests on his account, secondhand.

• question-verify-godfrey-nid-origin-against-mclachlan-room-39 — the open verification against his primary text.

• 2026-09-24: Of Block's account, only "intolerable" (p. 22) and two long passages from an unnamed officer (p. 23) are McLachlan's own text; the p. 23 passage uses an "E" grade (claim-block-2021-attributes-only-intolerable-to-mclachlan-room-39-p22, claim-block-2021-quoted-mclachlan-passage-uses-grade-e-against-a-to-d-scale). RMG holds Godfrey–McLachlan correspondence on writing the book (rmg.co.uk/collections/archive/rmgc-object-478556), unopened.