SEASONAL VARIATIONS / CAROLS: Mingled footsteps in the snow: Bayan Northcott discovers a knot of traditions tangled in the familiar Christmas doorstep serenade

YOU have survived the boozy bonhomie of the office party, risked impaling on somebody's plastic Christmas tree all the way home on the Tube and collapsed with curses of the season in a consoling armchair. Then you hear it: that unmistakable shuffling on the doorstep. There comes a dismal chant of 'Good King Wenceslas' - just enough to warn you it is neither a bevy of nice ladies collecting for charity nor the local church choir. After scarcely a verse, it breaks off in a tirade of knocking. Flinging open the door, you behold three small boys, their menacing mitts thrust out for a quid. You are about to send them scuttling with some latterday variant of 'Bah] Humbug]' Then you pause . . .

Quick dissolve to Camelot - or what the Lancashire poet of Sir Gawain and the Green Knight, writing towards the end of the 14th century, thought of as Camelot. Christmastide in late-medieval courts seems to have lasted some 15 days of jousting, hunting, feasting and dancing - to say nothing of the fanfares. 'Then the first cors come with crakkyng of trumpes,' we are told, plus a tumult of kettle drums, pipes and 'wylde werbles'. Wild warblings? Just possibly the poet was evoking drunken hoots and whoopings. But more likely he meant that the food was accompanied into hall by singing - to such words, it might be surmised from other medieval sources, as 'Nowell, Nowell: The Boar's Head that we bring here betokeneth a Prince without peer'.

Not that the early carol was exclusively a Christmas form or even, entirely, a Christian one - as certain pagan-cum-amorous reverberations of the holly and the ivy kind remind us to this day. Though most of the surviving manuscripts of the 14th and 15th centuries duly celebrate the Nativity, there are also carols on the Passion, the Martyrdom of St Stephen and even on political events - of which the so-called Agincourt Song is the best-remembered. What singled them out from other seasonal items such as Christmas hymns or motets, was their particular verse-refrain structure and their apparent association with processions and dancing.

But then they had evidently evolved directly out of one of the most ubiquitous secular pastimes of the 12th and 13th centuries for the aristocracy and common people alike: a kind of dance-song itself known as the carole, and mentioned in Sir Gawain. The verse-refrain pattern could well have developed from the alternation of solo dance-caller and chorus.

The problem for historians of the carol - as usual with cultures of the remote past - is that the vernacular side of the tradition tended to remain oral, and only the more cultivated examples were written down at the time. Yet the evolution of the latter repertoire up to the early 16th century was remarkable enough. For a start, it encompassed some of the most memorable surviving late-medieval lyrics: 'There is no rose of such virtue', 'To many a well have I go', 'I sing of a maiden that is makeless' - though no contemporary setting seems to survive of the latter.

The texts, moreover, often alternate lines of English, Latin and even French, and occasionally hint at dramatic presentation - in the welcoming, for instance, of a character called Sire Christemas. And the music, though always in triple time and almost never in more than three parts, presents a fascinating interplay between angular cross-rhythms and floridly flowing lines.

Whichever monophonic carols the common people were dancing and roaring out in the 15th century, the polyphonic repertoire was evidently for professional singers. It has been suggested it may have been performed by groups of travelling friars - a kind of Salvation Army of the Middle Ages. But by the early-Tudor period, even more elaborate carols were being written by such composers as Browne and Cornyshe, and possibly finding their way in to liturgical use. What put a stop to this entire tradition was the Reformation, with its animus in particular against the cult of the Virgin Mary. The Anglican dispensation demanded simpler settings - of which the late-16th century Coventry Carol would be an example - and those medieval manuscripts that survived the dissolution of the monasteries disappeared into dusty archives for the best part of 350 years.

In fact, the Puritans were to prove even more opposed to Christmas celebrations, and though the oral carol tradition, supplemented by broadsheets, seems to have carried on regardless into the 19th century, what might be called the composed or 'art' carol largely lapsed in Britain over the 150 years after the Restoration. The items that emerged from this period - often taking a long time to do so - were mainly straightforward hymns, without refrains. The tune to which we usually sing 'While shepherds watched' seems to have been around for almost a century before Nahum Tate wrote the words in 1700. On the other hand, Charles Wesley's 'Hark, the herald angels sing' only found its enduring setting with the importation of Mendelssohn's hymn tune in the mid- 19th century.

But by that time, the gothic revival, the Oxford Movement, the cult of Dickens and the coming commercialisation of Christmas had opened up a new, if more equivocal, era in the history of the carol. Arrangers began sanitising texts and tunes from the vernacular tradition, or rifling through such Continental heritages as the French Noel and the German Weihnachtslied for Christmas melodies to anglicise. In their lavish New Oxford Book of Carols, Andrew Parrott and Hugh Keyte trace the genesis of 'Ding] Dong] Merrily on high'. The tune is indeed an old French dance, but the cod-medieval words were a mid-Victorian forgery, and Charles Wood's dulcet Edwardian arrangement has come to epitomise for many the whole 'tradition' of the King's College Carol Service. Granted, the Victorians attempted original carol texts too, as the inclusion, in tomorrow's service, of Harold Darke's setting of 'In the bleak midwinter' reminds us. Christina Rossetti's sentimental verses were also set by Holst (it is not one of his better tunes) and in part by the young Britten in his 1932 sequence A Boy Was Born. But Britten illuminates his texture by superimposing a setting of one of the most haunting of genuine medieval texts, the Corpus Christi Carol.

By then folklorists had already noted down much of the surviving oral tradition while scholars were beavering away on those long-forgotten medieval manuscripts - though the results were to complicate the evolution of the carol still more. The village waits and church-gallery bands that once sustained the vernacular carol had already been under attack from ecclesiastical smoothies for much of the 19th century, as we know from Thomas Hardy. Yet, collecting in Sussex in 1904, Vaughan Williams was still in time to pick up 'On Christmas Night All Christians Sing'. The tune could well be medieval by descent, having a comparable lilt and profile to the 13th century Angelus ad Virginem. But in arranging it simply for chorus, Vaughan Williams could hardly avoid 'traditional' harmonies the Middle Ages never dreamt of.

Meanwhile, through the researches of such authorities as R L Greene, accurate medieval texts were finding their way into verse anthologies, such as the one Britten ransacked for his Ceremony of Carols in 1932. Then, in 1952, John Stevens published a comprehensive edition of 15th-century settings in the Musica Britannica series. This, too, was propitious. A number of post-war composers, including Stravinsky, had become interested in parallels between medieval and avant-garde techniques, and in the 1960s, Peter Maxwell Davies and Gordon Crosse in particular composed a body of settings and instrumental pieces extending medieval carol procedures. To do King's College justice, it has continued to support this development: amidst the usual hybrid arrangements, tomorrow's service includes a newly commissioned carol from Nicholas Maw. On the other hand, it is odd that the Festival of Nine Lessons and Carols continues to make so little of the genuine late-medieval tradition, which was, after all, the going style when the college was founded. Maybe next year . . .

Suddenly, you realise your three young visitants are still slouching on the step. 'Merry Christmas, Mister,' growls the eldest defiantly. You feel like demanding a few extra verses of 'Good King Wenceslas' for your pennies. But the kids have probably forgotten the words, if they ever knew them. Come to that, why should anyone remember such 19th-century doggerel? Yet the tune seems to be a real old Weihnachtslied - and they do remember that. Relenting, you pay up. After all, however unknowingly, the little bleeders are keeping up one of the oldest traditions of social music-making in Western history.

Festival of Nine Lessons and Carols tomorrow at 3.00pm on Radio 4 and at 6.15 on BBC 2.

(Photographs omitted)