Recent books on Elgar and CDs of his Enigma Variations still say only that various themes have been put forward but none of them fit. This assumes that you start at the beginning of each melody. A comparable mystery from the 15th century, solved only 40 years ago, was the anonymous English Mass cycle based on a chant labeled with the word "caput." Most illogically, this bizarre "head" stands at the tail of an antiphon, unleashing a lengthy melisma which (as a motto theme) graced many a musical masterpiece of the late Middle Ages.
In Elgar's case, the mystery tune comes neither at the beginning nor at the end of a melody, but in the middle. If you sing through "Rule, Britannia!" to the point at which the conventionally repeated "never, never, never shall be slaves" occurs, you find a brief motive which fits the Enigma theme, fast or slow, major or minor. It was first noticed by Theodore van Houten, who published the results of his research in The Music Review, No.37 (1976), pp.130-142, since which time it seems to have been largely ignored.
When Dora Penny (the "Dorabella" of Variation 10) asked Elgar about the enigma, he replied: "You of all people should have guessed!" But the penny never dropped. Had she looked at the tail of an old Victorian copper coin minted in the 1860s, she would have seen a helmeted Britannia, a sceptre in her left hand, her right resting on a shield bearing the superimposed crosses of St. George, St. Andrew, and St. Patrick. She is clearly ruling the waves, for at the lower left a lighthouse signifies watchfulness and guidance, while at the opposite side a ship is sailing away, doubtless to some distant corner of that Empire which Elgar celebrated more than once in his music.
As the ship leaves dock in Var.13, a fragment of Mendelssohn's Overture, Calm Sea and Prosperous Voyage is heard, the muffled sound of engines being suggested by a timpani roll, for which Elgar himself recommended using two pennies. Britannia is ubiquitous! And her theme song was of course the well-known refrain from Act II Scene 3 of Thomas Arne's masque of Alfred, written for performance at Cliveden Manor in 1740 to commemorate the accession of George I (1714) and the birthday of Princess Augusta. James Thomson wrote the words:
When Britain first, at Heaven's command,
Arose from out the azure main,
This was the charter of the land,
And guardian angels sung this strain:
Rule, Britannia, rule the waves!
Britons never shall be slaves!
In his program notes, Elgar states that "the principal theme never appears," by which he enigmatically meant "the principal theme 'never' appears," as indeed it does, quite unmistakably.
When this vital fragment reappears in The Music Makers ("sitting by desolate streams/for ever, it seems/the glorious futures we see"), there is a quotation from the Rule Britannia melody at the words "We vision an Empire's glory." If Elgar's patriotism sometimes went a little too far—as when he expressed the feeling that in certain circumstances British orchestras should play only music of British origin—his point of view deserves sympathy, for in his day no serious composer could hope to make a living by following the dictates of his own musical conscience.
We should also remember that Elgar often stayed with Richard Penrose Arnold (Var.5) in Britannia Square, Worcester, in the years just prior to the writing of the Variations when he was in an almost petulantly patriotic mood. After the première in June 1899, The Referee called the composer "in the best sense a 'feminist' in music"; and of course Britannia was and still is a female. Elgar's manliness, patriotism, and pride were tempered always by his sensitivity to the gentler aspects of life. Circumstances indicate that he regarded his wife Alice as his personal Britannia—one who with infinite patience and understanding would watch, guard, protect, and, in a quiet way, rule.
The reference to another and larger "theme" which goes with the variations as a whole sounds like one of his typical puns. "Theme" can mean melody or part of a melody. In a more general sense it is freely used in connection with poems, plays, novels, and the visual arts. As Herman Melville said in Moby Dick: "to produce a mighty book, you must choose a mighty theme." And Elgar, writing to Joseph Bennett, critic of The Daily Telegraph: "I hope some day to do a great work—a sort of national thing that my fellow Englishmen might take to themselves and love." Surely nothing could rank more highly as a mighty theme than Britannia as a symbolic representation of Britain and her Empire; and this thought may well have turned Elgar's mind toward the tune and text of a song already honored by Handel, Beethoven, and Wagner.