A list of commonly-believed misconceptions has long existed pertaining to Moeran's life, labelled collectively as the Moeran mythology. While each of these has been discredited, it may be wondered how and when they originated. The most dramatic of them was that the treatment for Moeran's seemingly serious injury at Bullecourt in May 1917 required the insertion of a metal plate to replace a damaged part of his skull. This story was in circulation by the late 1930s, as attested by Maureen O’Shea, daughter of the former proprietors of the Lansdowne Arms Hotel in Kenmare, Jim and Bridget O’Donnell. More recent dissemination of the narrative began with its inclusion in Geoffrey Self's 1986 book The Music of E.J. Moeran and it subsequently became one of Moeran's most distinguishing characteristics. Self had relied for his biographical information on anecdotal evidence provided by people who had known Moeran, most particularly the former director of the Radio Eireann orchestra Michael Bowles. Since the source of Bowles’ information can only have been Moeran, it is reasonable to suggest that the composer himself invented the metal plate story. A plausible scenario is that it was concocted by Moeran – possibly in conversation with Philip Heseltine – as an excuse for his behaviour under the influence of alcohol.

Alongside the metal plate, Moeran's other legacies of the First World War were believed to have been fragments of metal embedded too close to his brain to be removed safely, a disability pension and the trauma induced by several years of experience of the horrors of the trenches. Again, the modern propagation of each of these began with speculations that were based on anecdotal evidence – chiefly that of Michael Bowles – in The Music of E.J. Moeran, and again, the ultimate source must have been Moeran himself. In Self's defence, it must be said that he would have had no reason to disbelieve the evidence of Moeran's former friend, and since the archival material to which the author has had access was not available in 1986 – indeed even its existence was not known until many years later – Self would have had no means of either verifying or challenging Bowles’ assertions.