In Wellesley as "Johnstone, Edward"; Note that the William Johnstone of vol. 1 became William Johnston in vols. 4 and 5 on the basis in part of Blackwood Papers Cat. Edward Johnstone was William’s brother, tutor to the young Aubrey deVere, and apparently the rector of Warehorne of the Blackwood Papers Cat. However, Maurice Milne, ‘A neglected paternalist: William Johnston of Blackwood’s Magazine,’ VPR 28 (1995), 11-26, particularly 24-25; Milne spells Edward’s surname as Johnston, and it seems logical to give the brothers identically spelled surnames.
(Also in the Wellesley Index.)