In 1835 an ambitious plan, hatched by others, to produce a multi-volume edition of all the materials for the history of Britain, had foundered, and in July 1836 Kemble resolved to take upon himself the preparation of an edition of Anglo-Saxon charters, expecting that it would be complete in three or four volumes. The first two volumes of the Codex Diplomaticus Aevi Saxonici were published in 1839 and 1840, under the auspices of the recently formed 'English Historical Society'. Then, in December 1841, a magnificent twelfth-century cartulary came to light at Winchester, which proved to contain the texts of about 200 'new' charters. Kemble seems at first to have intended to abandon the Codex Diplomaticus, and to start again from scratch; but he failed to get the necessary backing for his new scheme, and thus after some delay continued with the Codex, now incorporating the additional charters from Winchester. The third volume appeared in 1845, followed by a fourth (1846), fifth (1847), and sixth and final volume (1848).
Kemble's Codex Diplomaticus Aevi Saxonici was a cornerstone for the perception of the English past which became established in mid-Victorian Britain. A paperback reprint of the Codex Diplomaticus will be published by the Cambridge University Press in 2011, in the Cambridge Library Collection. The reprint incorporates a Foreword by Simon Keynes, on 'J. M. Kemble and his Codex Diplomaticus Ævi Saxonici' (vol. 1, pp. v-xxv). A paperback reprint of Kemble's The Saxons in England: a History of the English Commonwealth till the Period of the Norman Conquest, 2 vols. (London , 1849), is available in the same series.
- Codex Diplomaticus: Cambridge Library Collection reprint (2011)
- Saxons in England: Cambridge Library Collection reprint (2011)