Surviving in the papers relating to Naval Operations at Holyhead, there is correspondence between the Senior Naval Officers at Holyhead and Liverpool. The series of letters represent an inquiry into why the DERBENT was 3.5 miles north of the approved shipping lane when it was attacked. The first page shows the sailing orders provided to the ship’s master, Arthur Falconer. The second page is the letter noting that the orders were capable of two interpretations and recommends changed the wording of future sailing orders.

Source:
ADM 137/942. Auxiliary Patrol Weekly Reports, Area XXII, Holyhead, 1917, ADM - Records of the Admiralty, Naval Forces, Royal Marines, Coastguard, and related bodies, The National Archives, Kew. pp. 356, 367.