As the town of Kenfig was constantly threatened by attacks from the Welsh it was rewarded by the lord who incorporated the town as a borough. The borough included old Kenfig, modern kenfig, Maudlam, much of North Cornelly, Marlas, Pyle and some of kenfig Hill. It was controlled from Kenfig Castle which housed the town's courts and jail.

As inhabitants of the borough, the townsfolk of Kenfig were known as burgesses and were entitled to various rights and privileges, which were written in a charter. The earliest surviving Kenfig charter is that of Thomas Le Despenser, granted in 1397. Several earlier charters must have been granted by various Lords of Glamorgan prior to this.

Burgages were allotted to the burgesses for about a shilling a year, this was paid to the lord. A burgage was a plot of land of a few acres on which a burgess could build his home and/or use the land as he wished. A Merchant Guild was formed by the burgesses in order to control the town's trade. Traders would have included tanners, cordwainers (shoemakers), smiths, armourers, chandlers, bakers, butchers and brewers. These people would have met in the Kenfig Guildhall, a building of great importance in the town.

The burgesses paid a fixed rent to their overlord and were granted freedom from their tolls arising from repairs to the town and its defences. Burgesses also had the power to hold their own courts to deal with anyone who abused the town's bye-laws. A portreeve or chief burgess was appointed to enforce these laws and take charge of the courts.

There were two fairs held annually at Kenfig. One, the patronal festival of the town's church, lasted for eight days starting from the eve of St James' Day (July 24th). The other was held on the Tuesday of Whitsun week. Both fairs were attended by many traders in Glamorgan.

Kenfig’s ordinances or bye-laws were quite comprehensive and reflect the importance of trading to the town.

Sanitation was obviously thought important as butchers were fined for throwing offal into the streets. Furthermore, the throwing of refuse or filth into any part of the town or within fifty feet of its walls was an offence.

Residents were responsible for keeping the pavements in front of their houses clean. Freedom of speech was limited – criticism or abuse of the corporation by any of the townsfolk could lead to imprisonment. Tennis playing in the high street was obviously considered a serious offence, a miscreant caught fighting in the street could be fined three shillings and five pence, but if caught playing tennis, a fine of five shillings was imposed. The ducking stool was used to administer justice in some cases.

The last of the ordinances of 1330 stated ‘Item, it is ordained that noe burgesses, stranger nor inhabitant shall reap or pluck any sedges nor any other roots in the said burrough to the annoyance, ruin and overthrow of the same’. This was an important early reference to the problem of sand encroachment at Kenfig.

There are frequent references to dramatic storms that battered this part of the coast during the 13th and 14th centuries. These would have contributed to sand encroachment but the main cause of the problem was that there was more sand exposed and available to be blown ashore. One very violent storm in 1228 caused extensive damage to Kenfig – many buildings were struck by lightening.

Attacks on Kenfig by the Welsh continued throughout the 13th and 14th centuries. During the 1220’s and 1230’s these attacks were inspired by Morgan Gam of Afan. In 1231 Morgan joined forces with Llywelyn, Prince of Gwynedd, whose army marched on South Wales. Morgan attacked Kenfig in 1232. The burgesses were prepared for this attack and moved their cattle to a place of safety. They took sanctuary in the castle and church after taking the strange action of burning much of the town themselves. When Morgan discovered that many of the town’s women, children, old and infirm had taken refuge in the church, he ordered his men not to violate the church and to spare the people within.

Morgan and his son did attempt to attack the castle, but because of strong defences and the bravery of those defending the castle, they were forced to retreat.

Kenfig was attacked again in 1243 by Hywel ap Meredith (Morgan’s cousin) and by Llywelyn the Last in 1257-8, during a general Welsh uprising in 1294-5 and when trouble flared up again in 1314.

In 1321, Kenfig was damaged when a group of important barons turned against Hugh le Despenser and attacked his property. The last reference to an attack was in 1405 – it is believed that Kenfig castle may have been attacked by the forces of Owain Glyndwr, but this may only be legend.

A survey carried out in 1307 states that there were 142 burgages in Kenfig and mentions a water mill and windmill. The water mill would have been on the river Kenfig at Llanfihangle and the windmill on higher ground near Maudlam cross, known locally as Mon Mawr or Twmpath y Felin Gwynt – Windmill Hill.

Hugh le Despenser acquired the lordship of Glamorgan in 1317 and a royal writ of that time states that the castle and everything attached to the town of Kenfig were worth £39 and 18 shillings. A further report made out at his death in 1349 states that there were 144 burgages in Kenfig. This would give an estimated population of 800.

Comparisons in the number of burgages in Kenfig with those in other major centres at this time are outlined below.

The Black Death hit Kenfig in 1349 and again in the years 1361 and 1369. This probably accounts for the drop in the number of burgages to 106 in 1375.

A charter was issued to the Kenfig burgesses in May 1423 by Isabella, Countess of Worcester confirming all their privileges, which indicates that the town was still thriving. Even as late as 1450 there are records of land changing hands at Kenfig. It is likely that the town was finally abandoned in about 1470 – the year in which the new St James Church was completed in Pyle. (This is the upside down church)