In a BBC Third Programme radio broadcast¹ on October 5, 1947, ‘The Spoken and the Written Word’, I.A. Richards noted that

Professor Havelock has suggested that we may see in Plato’s rejections of Homer the revolt of the writing mind’s mode of apprehension against the pre-literate mind’s other, less abstract and intellectual, ways of ordering itself.

This was 16 years before Havelock’s Preface to Plato was published in 1963 and contemporary with Harold Innis’s first communications publications which began with Political Economy in the Modern State in 1946.

Innis had long had contact with Havelock at the University of Toronto (see below and here) and now Richards had come to know of his work in 1946-1947 since Havelock moved at just that time from UT to Harvard (where he eventually became chairman of the Classics department).² Richards had been teaching at Harvard since 1939 and had close ties with the Classics department there and particularly with its star professor, Werner Jaeger (who had come to Harvard in the same year as Richards). In fact, ancient Greece, including translations from Homer and Plato, was to be central to Richards’ research and thinking in his 35-year Harvard career. A translation of Plato’s Republic by him had already appeared in 1942; his abbreviated translation of the Iliad, The Wrath of Achilles, would be published in 1950; further Plato translations would follow in the 1960’s.

Some background to this story is supplied by Havelock in essays he wrote in the 1980’s in the last decade of his life:

After encountering the work of Milman Parry [in 1943, see below], guided also by a reading of Martin Nilsson’s Homer and Mycenae (1933; for me still the classic work on the subject)³, and following (…) intuitions born of [my] pre-Socratic studies⁴ (…) I recall giving two or three public lectures at the University of Toronto on the topic of oral composition, and I suspect Innis was one of those who heard them, at a time when he was thinking along similar lines in his own field.⁵ (The Muse Learns to Write: Reflections on Orality and Literacy from Antiquity, 1986)

…phrases like “oral formula” and “oral composition” in connection with Homer had come into currency at Harvard about the time, just after the Second World War, when I joined the faculty [in 1947]. This was because of the close connection of Milman Parry [1902-1935] and Albert Lord [1912-1991] with that university. (…) [Parry’s] doctoral thesis, L’Epithete traditionelle dans Homere, was the founding document of the modern Homeric oralist theory of composition. It was published in Paris in 1928 (…) By the years 1946-7, Parry’s thesis, reinforced by articles [he] subsequently published in the Harvard Studies in Classical Philology,⁶ was gaining notice at Harvard, and his pupil Albert Lord was able to begin giving recordings of performances of the Balkan material Parry had collected, some of which I heard myself. (…) After Parry, the oral-literate question (as it was later to become) received impetus from a very unexpected quarter when Harold Innis published The Bias of Communication (1951). (…) Innis (…) drew some support from the Homeric model provided by Parry, which tempts me to add a brief personal note. Innis and I had known each other for some years⁷, not intimately, but with mutual regard. During the summer of 1943 I read Parry’s  work — I should have read it earlier — and later gave one or two public lectures on Homer and oral composition at the University of Toronto. Innis came to hear them and at once connected what I was saying with what he had been contemplating in a different context [namely, Canada’s pulp and paper industry and its relations with the technology, content and social effects of printing]. (‘The Oral-Literate Equation: A Formula for the Modern Mind’, 1987)⁸ 

Perhaps as prompted by Havelock, but more likely already by Parry’s work as brought forward by Lord at Harvard, Richards in this late 1940’s period was looking into these questions of the nature of oral composition and its differences from literary writing.  A marker of this research is given in his 1950 ‘Introduction’ to his translation of the Iliad, The Wrath of Achilles:

A very large proportion of the Iliad consists of line-beginnings, [complete] lines, and line-endings which the poet could use very freely over and over again, knowing them to be metrically satisfying and sufficiently neutral as regards the context of what he was saying to raise no difficulty for him or his audience. Most of the stock epithets annexed to the characters, the formal openings and transitions, and many of the similes and descriptive fillings are essentially ready-made rests, for the poet and his hearers, by which the strain of composition, and of comprehension for the listeners, can be lessened. (11)

The technical world ‘rests‘ is italicized by Richards and is a silent reference to Parry’s pioneering work and in particular to Lord’s first publication of that work in 1936 immediately after Parry’s sudden death in 1935: ‘The Singer’s Rests in Greek and Southslavic Heroic Song’. ⁹

It may be that a particular sign of this intellectual exchange between Havelock, Innis and Richards (and eventually also McLuhan) is the story of the invention of writing by the Egyptian god Theuth in Plato’s Phaedrus (274ff). As detailed here, this story was cited repeatedly by Innis (beginning in 1946) and McLuhan (beginning in 1953); but it also appears at length in Richards’ 1947 BBC radio broadcast as follows:¹⁰:

Socrates may have had a prejudice against writing. Plato gives him — in the Phaedrus (274c-277a) — a very curious little story about the invention of the letters:
”I heard, then,” says Socrates, “that at Naucratis, in Egypt, was one of the ancient gods of that country, the one whose sacred bird is called the ibis, and the name of the god himself was Theuth. He it was who invented numbers and arithmetic and astronomy, also draughts and dice, and, most important of all, letters. Now the king of all Egypt at that time was the god Thamus . . . To him came Theuth to show his inventions, saying that they ought to be imparted to the other Egyptians. But Thamus asked what use there was in each . . . when they came to the letters, ’This invention, O King,’ said Theuth, ‘will make the Egyptians wiser and will improve their memories; for it is an elixir of memory and wisdom that I have discovered.’ But Thamus replied, ‘Most ingenious Theuth, one man has the ability to beget arts, but the ability to judge of their usefulness or harmfulness to their users belongs to another; and now you, who are the father of letters, have been led by your affection to ascribe to them a power the opposite of that which they really possess . . . you offer your pupils the appearance of wisdom, not true wisdom . . . for they will read many things without instruction and will therefore seem to know many things, when they are for the most part ignorant and hard to get along with’...”
“Socrates,” says Phaedrus, “you easily make up stories about Egypt or any country you please.” But Socrates goes on:
“He who thinks, then, that he has left behind him any art in writing, and he who receives it in the belief that anything in writing will be clear and certain, would be an utterly simple person . . .every word, when once it is written, is bandied about, alike among those who understand and those who have no interest in it . . . for it has no power to protect or help itself.”
Instead of such [written] words, the true teacher will use “the legitimate brother of this bastard [sort of communication] . . . [planting] in a fitting soul intelligent [spoken] words which are able to help themselves and him who planted them, which are not fruitless, but yield seed from which there spring up in other minds other words capable of continuing the process for ever, and which make their possessor happy, to the farthest possible limit of human happiness.“
Socrates is notably serious here.

Havelock references this same section of the Phaedrus both in Preface to Plato (1963) and in Communication Arts in the Ancient World (1978).  The guess here is that he also cited it much earlier in lectures in Toronto and Harvard in the 1944-1946 period. The story was then cited — at second or third or forth hand (via Havelock citing Plato citing Socrates citing Thamus) — by Innis in Political Economy in the Modern State in 1946¹¹ and by Richards in his BBC talk in 1947.