Kelvedon is placed within a wide bend of the Blackwater, near a crossing of that river; its Saxon name, first recorded in 988, reflects this river-valley location. Settlement grew up on terrain adjacent to, but above the level of, the river meadows. Three miles south of Coggeshall, it is almost as close to Witham to the south-west, and to Braintree a little further to the north-west. Its High Street conforms fairly closely to a Roman route from Colchester to Chelmsford, with Kelvedon close to the mid-point between the two. This could be considered its competitive environment as a market centre.

There is not a great deal that can be said of medieval Kelvedon, for it has received relatively little attention from historians and is not yet covered by the Victoria County History. Nor are there strong grounds for considering its character urban; Kelvedon's inclusion in the Essex component of the Extensive Urban Survey and description therein as a "medieval town" is hard to justify from the evidence. Its site did, however, host a modest Iron Age settlement, succeeded by a small town in the Roman period; the latter, known as Canonium, had a civil character, though with some defences added subsequent to its foundation. The Roman road between Colchester and London ran alongside one edge of this town, with a minor road passing through the town further south. The town was already in decline before imperial authority in Britain came to an end. Subsequent fresh settlement by Saxons is evidenced by a cemetery to the east of the site, on the opposite bank of the Blackwater; finds there indicate burials of some individuals of elite status. Precisely where a Saxon settlement was located is unknown, but there is no compelling reason to think it had, or came to acquire, an urban character.

Medieval Kelvedon was based around a linear street oriented south-west to north-east, but this represented not a continuous settlement, but rather a connection between two originally separate foci of settlement. One of these, probably the older, was close to the church of St. Mary at the south-west corner of the site; this end of the through-road deviated briefly as it intersected with a second, running south-east to north-west. The eastern branch of the latter, now Church Street, led to the church, while the western branch later turned south in the direction of Maldon and its port. No church is mentioned in Domesday, and its origins and ownership are obscure; its nave dates to the twelfth century, but aisles added on either side during the thirteenth point to population growth in the parish. The second, and secondary, focus of settlement lay half a mile north-eastwards of the first, at the crossing of the Blackwater, known as Easterford – a name that may occasionally have been used for the entire village and parish by or after the close of the Middle Ages, though the identification could alternatively have originated with a separate manor there, held by the de Kelvedon family and so known, confusingly, as Kelvedon Hall. At Easterford the High Street was crossed by another road which ran, south of the river, to Coggeshall.

The archaeologist who excavated Canonium included in his report a site plan describing post-Conquest Kelvedon as a planned settlement and showing a row of properties of consistent sizes along the south side of the High Street, between the southern crossroads and the ford. He argued that the part of Kelvedon formerly colonized by the Romans had been re-divided into eight plots, each 50 poles by 20 poles in size, at some point before a manorial survey of 1294, which shows alterations to this tenemental arrangement. The subsequent concentration of settlement into two foci he considered to have occurred during the twelfth century, in a necessarily unplanned fashion due to the division of landlordship between several manors.[K.A. Rodwell, The prehistoric and Roman settlement at Kelvedon, Essex, Council for British Archaeology Research Report 63 (1988), pp.134, 137]. The built-up area around the High Street seems to have remained discontinuous throughout the medieval period; the line of scattered dwellings only began to become more dense after Kelvedon captured increasing business during the eighteenth century as a staging-post and stopover for travellers using what was an important route connecting London with Colchester and the East Anglian interior, and this build-up was not completed until the next century.

Domesday's coverage of Kelvedon shows two manors there, later known as Church Hall and Felix Hall, each with its own mill on the Blackwater; neither was especially large. Each held property along the High Street and was likely to have had an interest in a market at Kelvedon. The Church Hall manor-house is believed to have been situated on Church Street in the thirteenth century, but relocated in the next to a site a little south of the parish church. This manor had been granted to the Abbey of Westminster in 998, and the abbot was its lord at the time of Domesday. Rodwell suspected the planned layout he posited, along with construction of the parish church, to have been contemporary with the abbey's acquisition of the manor; that agency seems likely, though the dating doubtful. Control over the advowson of the church seems to have come into dispute between the abbey and the Bishop of London, until in 1331, perhaps following a court judgement or settlement between the parties, the king confirmed it to the abbey. An attempt by the abbey to develop Kelvedon in a planned manner could have taken place at any point from 998 on, but would be more consistent with the post-Conquest trend to establish partially commerce-based settlements along major communication routes. Certainly the Domesday entry for this manor shows the abbot of that time seeking to extract substantially more profit from the manor than its assessed value, while expansion of the abbey's holdings onto assarted land is documented in Stephen's reign.

The extent of the manor of Felix Hall, a corruption of Fillolleshall, is less certain, but the Georgian manor-house was about a mile north of the church. That manor incorporated, or later absorbed, some other smaller estates that were at least partly within Kelvedon parish and had manorial status, possibly including that known as Kelvedon Hall. Before the Conquest what would become the core of Felix Hall was held by Guthmund, a royal thegn and the brother of the Abbot of Ely; after the Conquest it became part of the estates of Hugh de Montfort, though he was not resident at Kelvedon. Although smaller and less populous than Church Hall, Felix Hall is seen to have significantly increased the size of the sheep flock pastured there, from 40 in 1066 to 140 in 1086.

It was John Filliol who, in 1312, acquired a licence for a market and fair at his manor at Kelveden. Two registrations of the licence are recorded for the same date (May 28): one for a Thursday market and a fair over the three days following Whitsunday, the other for a Monday market and a fair on Whitsunday itself and the days immediately adjacent. It seems unlikely that whichever was the initial grant would have been so promptly accused of being in conflict with some other nearby market, though not impossible – the Templars' market at Witham was on Thursdays and that of the Bishop of London at Braintree on Wednesdays, and either of those interests might have been at the royal court when the licence was granted. Nor is it probable that, as Letters speculates, the intent was to licence markets on both days – this could have been done with a single licence and does not explain the small alteration to the timing of the fair. Letters' alternate suggestion that one licence superseded the other is easier to swallow; the appearance is that Filiol had a change of mind that day, though this might have been upon learning of a potential conflict with, and risk of challenge from, a neighbouring market. Which of the two licences was the valid one, however, we do not know. It may be noted that the fair was not associated with the dedication of the church; this suggests the Filiol family were neither founders nor major patrons of the church. That the court was at York when the king granted the licence makes it likely John Filiol was a member of the royal entourage at that time.

The Filliol family may have originally been based at Crawley (Bucks), where there was a manor named after it; Baldwin Filliol is seen expanding this holding in 1198. The derivation of the surname combined with a family seal depicting a baptism officiated by a bishop and attended by a monarch has led to the notion that the family founder may have been the godson or bastard of some potentate [Thomas Wright, The History and Topography of the County of Essex, vol.1, London, 1831, p.261]; though we should be sceptical about self-aggrandizing origins legends, the earliest documented Filliol in England (1175) was named William, and a like-named father could easily have been born in the reign of William Rufus or even that of the Conqueror. It is probable enough that some family member accompanied or followed the Conqueror (or one of his principal supporters, such as Hugh de Montfort) to England.

The Filliol family also held a manor at Kelvedon since at least 1206, when the Pipe Roll records Baldwin holding three knight's fees there. Besides that military service, the lordship also entailed castle-guard obligations at Dover castle (later commuted), which points to the association with Hugh de Montfort, Constable of England. However, the manor was said to be part of the Honour of Haughley; Haughley (Suff.) was held of the king in 1066 by the aforementioned Guthmund, known as 'Guthmund of Haughley' (for that was the largest and most valuable of his estates), and in 1086 by Hugh de Montfort who, intending it as the caput of the honour created for him, replaced a fortified Saxon manor-house with a castle and relocated the Saxon market next to the castle bailey, though it was left to Hubert de Burgh to licence the market (1227). It was probably a next-generation Baldwin Filliol who was, around mid-thirteenth century, mesne tenant of a manor at Bradwell, occupied by the Dagworths, a few miles north-west of Kelvedon, as well as tenant-in-chief of the manor of Toppingho in Hatfield Peverel, a slightly greater distance south-west of Kelvedon; the latter manor Baldwin had in 1269/70 leased to John le Ferrun of London, and subsequently his widow. Baldwin died 1279, leaving as his heir his son Thomas (b. 1267), but there is no reference to Kelvedon in his inquisition post mortem, and it had likely earlier been inherited by Richard Filliol (first mentioned 1229), who was presumably Baldwin's brother. In 1251 Richard had purchased a grant of free warren at Kelvedon and at Little Baddow, and in 1253 the right to hunt hare and fox in the royal forests of Essex. Such grants may have been easier to obtain because of his royal service: in 1250 Richard was replaced as Essex's coroner after being appointed the king's steward of the forest there. But, as he aged, he sought to avoid being excessively called upon, for in 1253 he obtained a life exemption from being made coroner, forester, verderer, escheator, or sheriff, and two years previously had been exempted from serving on juries or assizes – Baldwin gaining similar exemptions in 1255. This did not, however, prevent Richard being part of a royal retinue to accompany Henry III to Gascony in 1253.

Richard Filliol was succeeded by son John (b. ca. 1236) in 1260; this John appears to have been our market licensee, despite his advanced age when he took that initiative – later in the same year of the licence he too was granted exemption from serving on juries and assizes, on account of his age (he being referred to as John Filliol senior). There is no evidence to associate any of the Filliols with development of settlement around Kelvedon's market, nor that the family was more involved with the local church than any other prominent parishioner. No other market licence is associated with the family, even though Richard's inquisition post mortem, along with other sources, reveals other estates than Kelvedon – or at least revenues from such – all in that same region of Essex (Coggeshale, Little Baddow, Mowden, Hockley, and Tolleshunt), most acquired through marriage into the Fitz-Walter family. John is also seen in possession of land at Boreham (near Little Baddow) and for a while also held property in Suffolk, as guardian of the heir of his kinsman, Baldwin Filliol. Further Essex lands are found in the hands of individuals of this surname, though the relationship between them is not clear.

Certainly the family was well enough rooted in the county gentry that our licensee John Filliol could overcome his association, in younger days, with the rebels against Henry III and be chosen to serve as a knight of his shire for the parliaments of 1290, 1295, 1297, and 1300. Yet his roles in the royal administration of Essex seem comparatively slight, limited to occasional shared responsibilities for organizing squadrons to patrol the coastline and, in 1303, purveying grain for the use of an army sent into Scotland. While a John Filiol was a frequent commissioner of banks and ditches in Sussex, there is nothing to connect him with the Essex man, except perhaps kinship. For at John Filliol's death ca.1317 his heir was his nephew, another John Filliol, qualified as 'senior'; the latter's estates were at his death (1332), divided between two underage sons, of whom the elder, Richard, inherited most of the Essex property, and John junior much of the remainder; but both died childless, and in 1346 a sister, Cecily, was described as the only living child and heir of John senior. She brought the Crawley manor and that at Kelvedon to her marriage into a junior branch of the Bohun family, which held it until the male line was extinguished in 1499. Otherwise, the Filliol family is little evidenced in Essex in the post-plague period. The Filliols and/or Bohuns must have worked to consolidate Kelvedon and other properties acquired within its surrounding region into an administrative entity, for in 1433, long after they had ceased to be the manorial lords, we hear that the manor of Fillolleshalle in Kelvedon had appurtenances in Feering, Great Braxted, Messing, Inworth, Bradwell, Easthorp, Copford, Terling, and Tolleshunt; these lands may have been intended to supply the manor-house at Kelvedon and generate income through sale of surplus produce through Kelvedon's market.

It seems reasonable to assume that some kind of market activity was taking place at Kelvedon before the grant of the market licence; the volume of commercial travellers passing through the village was evidently sufficient to warrant licensing a fair at the same time. Where the market was held is uncertain, but the likeliest site would have been the southern crossroads, formed by Church Street and the High Street. A number of things support this: the junction was said to be the site of the communal well in 1491, when a resident bequeathed funds for its maintenance; the Abbot of Westminster had a residence on the corner of the junction from at least the early sixteenth century; one of the buildings facing onto the junction originated as a public building of the fifteenth century, with an open ground floor that faced onto the junction, and may well have served as a market-hall. Another site facing onto the junction, rebuilt as the Angel Inn in the sixteenth century, belonged to Felix Hall.

There is no evidence as to how well Kelvedon's market performed, or how long it remained in operation. John de Filliol may have intended primarily that it service his tenants in Kelvedon and Filliol properties in the surrounding area, both as a supplier of necessaries and an outlet for produce of their labours. That produce was primarily grain in the late fourteenth century; the abandonment, by 1396, of one of the mills at Kelvedon reflects reduced demand following the population loss to plague outbreaks, with Westminster Abbey compensating by increasing cultivation of barley on its estates, for the production of ale. Sheep-farming was also on the increase during the latter half of the fourteenth century, judging from the number of abbey fleeces sold, although wool prices were falling – in part because of the expansion of the flocks – so that the activity was being cut back by the last years of the century [R.H. Britnell, Growth and Decline in Colchester, 1300-1525, Cambridge University Press, 1986, pp. 145, 150, 153, 155-56]. But it was perhaps the availability of more wool at lower prices that encouraged some growth of the cloth industry. Kelvedon has been included by a number of historians in lists of the principal Essex centres of cloth manufacture in the fourteenth and fifteenth centuries [e.g. Michael Gervers, The textile industry in Essex in the late 12th and 13th centuries: a study based on occupational names in charter sources," Essex Archaeology and History, ser. 3, vol. 20 (1989), note 63, citing other sources]. Despite this, occupations related to the cloth industry – or indeed to any artisanal activity other than food trades – are little in evidence there. In 1333 we hear of a Henry le Taillour, while in 1472 John Cumwell of Kelvedon is described as a tailor, although his son only as a labourer, while a glover is mentioned at the same time; but this is very thin evidence. Nor do we hear of shops being part of Kelvedon property transactions, and there is only one instance (1376) of a landless messuage changing ownership. It is perhaps stretching things to consider Kelvedon a town at any point in the Middle Ages, for we cannot rely on the presence of a market to warrant such a categorization.