The Church of Irvine which, before the Reformation belonged to the monks of Kilwinning, is of very ancient date, probably originating at the same time as the town.
Tradition tells us that St. Inan, a most holy confessor and doctor of Christianity, died at Irvine of which place he was patron. He is said to have flourished in 839, his festival being the 18th August. The cell of this holy man may therefore have been the origin of the church, but, in later times, when the Celtic Church was superseded by the Church of Rome, his name as patron was removed and the Church of Irvine was rededicated to the Blessed Virgin Mary. This is shown in the confirmation by James II in 1451, of the grant by Lady Alicia Campbell of Loudon, in which the church is called the "Parish Church of St. Mary the Virgin of Irvine". St. Inan had not even an altar dedicated to him in the church, and Lady Day or Mary Mass, has long been held as the festival day of the town.
Beside the pre-Reformation Church, which stood on part of the site of the present building, there was a little chapel to the south-west, dedicated to the Virgin Mary. It stood on the bank of the river, near the parish church, in an area near the chapel well. When the field, as it was then, was purchase by the Town Council in 1761 a digging operation was undertaken during which foundations of walls were uncovered which, in all probability were those of the little chapel.
In 1205 an agreement was entered into at Irvine between the Burgesses and the whole community and Brice of Eglunstone by which the Burgesses granted certain lands to Brice for which he paid the Parish Church of Irvine an annual 10 shillings sterling in the name of feu ferme. [This type of feudal tenure which came to pre-dominate in Scotland was tenure in return for a sum of money, generally paid twice a year, at Whitsunday and Martinmas. This was known as feu ferme tenure, and the amount paid in perpetuity was known as feu duty.]
This building, probably the first Church, was built small and rude of freestone ashlar. It was cruciform in shape, with a representation of the Cross on its ground plan. An arm was attached to each side, a little midway, and called the North and South Transepts; for the shaft of the Cross always lay Eat and West, and it was lit by narrow lancet windows turned with two arches. These early churches were oriented to the sun, so that the light could stream through the eastern door at sunrise.
In pre-Reformation times, the old church was divided and furnished according to the Roman Catholic notions. At the upper end, the raised Choir or Chancel was railed off by a screen. The lower end was called the Nave. The Choir was an inner sanctuary where the privileged enjoyed seclusion at prayer and Holy Communion. The Choir section alone was paved. Worshippers brought their own cushions or stools, a necessary convenience whilst kneeling at prayer.
The Parish Church of St. Mary the Virgin of Irvine became enriched by various endowments, the earliest of which is dated 1323-4 and, as time went on, it gradually assumed an importance superior to the ordinary run of parochial churches.
Besides the chaplains for the ordinary service of the church, it had endowments for chaplains and chaplaincies at the altars of St. Katherine and St. Ninian; the altar of St. Michael, in the new aisle;
the altar of St. Conval the Confessor, St. Stephen and St. Sebastian, the Martyrs in the south aisle;
the altar of the Blessed Virgin Mary; the altar of St. Salvator and St. Thomas the Martyr, in the aisle built on the north side of the nave;
the altar of St. John the Baptist, Christopher the Martyr, and Ninian the Pontiff.
The outline of the chapel would, probably, in its original state be oblong, but the addition of the three other aisles must have considerably added to its appearance, outwardly; and, the addition of the many altarpieces, must have correspondingly added to its appearance in the interior.
The chapel was from time to time enriched with many grants, bestowed upon it by individuals "seized with compunction for the safety of their souls."
Charter by Mr William Cunninghame, Vicar of Dundonald, of various lands and rents for support of two chaplains in the Parish Church of Irvine. This Mr Cunninghame was perpetual vicar of the church of Dundonald, and son of the Lord William de Cunnighame, Lord of Kilmaurs.
In addition to the above grant, he granted another charter of various lands and rents for the support of two chaplains in the Parish Church of Irvine. This charter was confirmed by James I on 28th July 1426, reserving always the services due to the king and the royal burgh of Irvine, from the tenements and lands specified in that charter.
Instrument of Sasine in the yearly rent of 5 merks granted by Lady Alice Campbell of Lowdonhill for the support of a chaplain at the altar of St. Michael in the Parish Church of Irvine. [under Scots law an Instrument of Sasine was a legal record for the transfer of property, usually land or rights to land.] Her grant was confirmed by James II in January 1452.
It has to be remembered that at this time that the towns now existing along the length of the River Irvine were not yet in existence, so it would be to the church in Irvine that those wishing to make endowments would make them.
A charter by Rankin Brown, Burgess of Irvine, granted to the "Curate of the Parish of Irvine, and five other Chaplains, certain annual rents for masses, in order that they say a private mass each day, with procession and chant solemnly for the good estate of the most serene Prince James the Fourth, most illustrious King of Scots, and Dame Margaret his most illustrious Consort; and for the souls of his progenitors and successors."
There is a stone, now sadly faded, built into the South-West wall of the present Church thought to commemorate the gift.
The letters M.Q. for Queen Margaret and the year 1506, the date of the grant; or the stone may commemorate a visist which James IV and his Queen paid to Irvine and Kilwinning when they viewed the "reliques" and made an offering of 14/- to the Abbey and St. Mary's Church. This stone was originally built into the Chapel of St. Mary and afterwards transferred to the walls of the new building in 1774.