Among the more important letters are those from Sir Walter Raleigh, 1906, 1910-1911, 1920, concerning Grierson's work on Elizabethan literature; from Robert Bridges, undated, chiefly concerning the Society for Pure English tracts, and also expressing his dislike of Donne's poetry, and from C M Grieve ('Hugh MacDiarmid'), 1925, concerning his own poetry, his aims for Scottish literature in general, and the revival of the Scots vernacular.

A typescript of Grieve's poem, 'I heard Christ Sing' (folio 59), is included with the correspondence, having been submitted to Grierson for approval of the dedication.

The other correspondents include Sir James Barrie, Gordon Bottomley, Joseph Conrad, John Galsworthy, John Masefield, Maurice Maeterlinck, Sir Herbert Read, Logan Pearsall Smith, Hugh Walpole, and Sir William Watson.