1. In 1545 John Leland published the present work, the fruit both of his antiquarian research and travel. The poem’s premise is that a swan cruises the Thames downstream from Oxford as far as Greenwich, describing the important topographical features it sees along the way and giving Leland a chance to expatiate on them in his accompanying commentary notes, some of which are copious. Although in one sense the poem may have been partially written as an excuse allowing Leland to disgorge a large mass of antiquarian information in his accompanying commentary notes, it has a certain interest for modern readers in its own right, since it is Leland’s most ambitious poetic work. Although containing plenty of felicities, the poem has two features many modern readers will probably regret. It is 700 lines long, and the swan’s journey is completed by line 400, with the remainder being given over to fulsome praises of Henry VIII. Even if we concede that a certain amount of such courtly flattery was requisite and inevitable, lavishing 300 lines on it seems entirely disproportionate, and has the effect of consuming space that might better have been devoted to more detailed descriptions of individual sites visited by the swan (for, in candor, most of these descriptions are very perfunctory). The poem’s second feature that might be regarded as a miscalculation is that it is written in hendecasyllables. The Romans reserved this meter for short, epigram-like poems (by Catullus and Martial) and tragic choral passages (by Seneca). In reading 700 consecutive hendecasyllables, I, for one, discover a certain rinky-tink quality never obtrusive in such shorter stuff. This, of course, is a matter of taste, and other readers may disagree. Questions also arise whether, by the standards Humanists strove to imitate, the hendecasyllabic line has sufficient weight and dignity for a lengthy and serious work.
2. I do not think I am the first reader to discover both these faults in Leland’s poem. In the course of his Britannia William Camden — who also occasionally inserts snatches of Κύκνειον ᾇσμα — includes quotations from an otherwise lost poem of his own, Connubium Tamae et Isis (“The Marriage of Tama and Isis”). This, too, was a topographical poem that takes its organization from a trip down the Thames, this time from its source in the Cotswolds and at least as far as London (we do not know how much further downriver Camden continued his imaginary tour of inspection). The description of sights seen along the way are contain considerably more circumstantial and historical detail. And the Connubium is written in the dactylic hexameters one would expect. One regrets the loss of this poem, its fragments look as if they come from a major work of considerable importance. It is impossible to read them without concluding that Camden wrote his poem in response to Leland’s earlier one, as a kind of corrective.
3. But in a sense, one suspects, the poem was only written to give Leland the chance of publishing his accompanying commentary, as a device for placing these diverse antiquarian notes on the printed record. His standard procedure is to mention some location in the poem by using the Celtic place-name he at least thought it had possessed in the Roman (or, failing that, Saxon) period. In each such case, this allowed him to write an explanatory note, some of which are of considerable length. In result, the volume as a whole contains 79 (unnumbered) pages; of these, the poem itself occupies only 29, the rest being devoted to prefatory material and the commentary notes, arranged alphabetically. Leland refers to this supplementary material in his dedicatory epistle addressed to King Henry:

Addidi praeterea, tanquam ad coronidem, quorundam antiquorum nominum et catalogum et interpretationem, ut hinc Britannicae antiquitatis cognitio a multis toties anxie quaesita, at non inventa tamen, nunc quasi reperta videatur.

I have further added (as if as a colophon) the names of some ancient writers and an interpretative catalogue, so that from this an understanding of British antiquity (so often anxiously sought by many, yet not found), will now seem to be discovered.

His deprecatory description of this large mass of material as a “colophon” must have been written with tongue planted firmly in cheek.
4. Although Leland’s commentary notes presumably have an interest for the history of British antiquarianism, here I present only the poem, with my own annotations. In many instances, all that is necessary is to gloss ancient place-names with their modern equivalents, which can be done within the translation itself. Κύκνειον ᾇσμα was printed at London in 1545, its printer (J. Herford) is not identified on the title page. It was reprinted at London by John Streater in 1658.
5. I should like to thank Mr. Oliver Harris for suggesting a number of ways in which this edition could be corrected and improved.