Rather than simply identifying a potential problem (FMD) and a solution (inoculation), Deasy's letter sets the stage with a grand consideration of Irish economic history, past present and future. A thread of conspiracy-theory runs through it all, and after Stephen finishes reading the letter, Deasy tells him that conspiracies are thwarting his own efforts to call attention to the FMD problem: "I am trying to work up influence with the department. Now I'm going to try publicity. I am surrounded by difficulties, by... intrigues by... backstairs influence by..."
The "department" is presumably the "department of agriculture," described in the letter as displaying "pluterperfect imperturbability" in the face of alarming information. (God, or Joyce, knows what Deasy means by pluterperfect, but the author liked the neologism enough to use the two-word phrase again in Oxen of the Sun). Deasy would like the department to consider the potential impact of FMD on "our cattle trade," which (if prompt action is not taken) may go "The way of all our old industries." (The glories of many of these industries are enumerated by the Citizen in Cyclops: "Where are our missing twenty millions of Irish should be here today instead of four, our lost tribes? And our potteries and textiles, the finest in the whole world! And our wool that was sold in Rome in the time of Juvenal and our flax and our damask from the looms of Antrim and our Limerick lace, our tanneries and our white flint glass down there by Ballybough and our Huguenot poplin that we have since Jacquard de Lyon and our woven silk and our Foxford tweeds and ivory raised point from the Carmelite convent in New Ross, nothing like it in the whole wide world.")
Deasy thinks of a scheme in the 1850s and 60s to make "Galway harbour" a translatlantic port housing a Galway-Halifax steamship line, and of a "Liverpool ring" which allegedly sabotaged it to protect its own shipping interests. Citing Robert M. Adams' Surface and Symbol, Thornton concludes that there is no evidence of any such conspiracy and "Deasy is mistaken again." Gifford summarizes the sorry history of the project and concludes that "the evidence, on the contrary, points to the maritime incompetence of the promoters." Looking forward in time, Deasy predicts that a "European conflagration" (one would erupt in 1914) might disrupt shipping of "Grain supplies through the narrow waters of the channel" separating Ireland from England and Scotland.
It is not certain what exactly these disasters past and future may have to do with "That doctrine of laissez faire which so often in our history [. . . ]," but presumably Deasy is urging the Department of Agriculture to adopt a proactive, interventionist policy, rather than passively waiting for foreseeable problems to wreak havoc on the economy.