The Norman Conquest was a major turning point in the history of Holy Trinity but despite its new status as a Benedictine Priory and its reformation as a monastic community the church did not lose all its pastoral responsibilities towards the laity but continued to function as a parish church throughout the middle ages and beyond.
There has been some dispute as to whether a separate church dedicated to St Nicholas was provided on the site for lay worship or whether lay services were focussed on an altar dedicated to St Nicholas within the nave of Holy Trinity. The evidence of the surviving fabric (the earliest of which dates from a late twelfth-century rebuild) suggests the latter was the case, at least during the later middle ages when references to a 'parish of Holy Trinity' are as common as references to the appointment of vicars to the altar of St Nicholas in Holy Trinity from the thirteenth century to the fifteenth.
The construction of a new stone belfry tower by parishioners of St Nicholas above the chapel of St Nicholas in 1453 indicates that lay association with a parish of St Nicholas continued strongly throughout the medieval period. Wealthy parishioners such as the merchants John de Esshton (in 1384) and Thomas Nelson (in 1474) founded chantries in the church supported by rents from properties in the city. In 1538, when the priory was dissolved, the parishioners were allowed to continue to worship in the nave, which has thus survived as a parish church to the present day. The chancel of the former priory church was demolished following the collapse of the priory's central tower in 1551.
Typically we know most about the wealthiest parishioners — those who were active members of the church and who left substantial material gifts to it. We know that such people were not necessarily typical. Not all of the parish's residents would even have been nominally Christian: in the twelfth and thirteenth century Micklegate was also home to at least some of York's small Jewish community, whose synagogue was in Coney Street across the river. But in York at least our strongest surviving evidence postdates the expulsion of the Jews in 1290 and mainly records matters of probate or litigation before the church courts.
While without doubt Holy Trinity was an active and important parish church throughout the medieval period, it remains more illuminating to study it as part of a group of neighbouring and associated parishes than as a single parish in isolation. There were two chapels at ease provided for parishioners living at some distance from Holy Trinity: St James on the Mount and St Helen in Dringhouses (the latter was not replaced with a full parish church dedicated to St Edward until 1853).
But, much more importantly than this, the scanty, dry evidence of wills and church court records, legal agreements and financial accounts, also show a considerable daily interchange of social and economic activities between friends and families living in the rural Ainsty and intramural households within the Micklegate neighbourhood. Even more so within the city itself; the tiny parishes carved out around individual small churches after 1100 were not nearly capacious or sufficiently clearly bounded to operate entirely separately from each other.
Micklegate was a wealthy, mercantile neighbourhood by the end of the fourteenth century. Many of its inhabitants were not content to see their religious affiliations restricted to a single small church. Typical in this respect was the family of the Nicholas Blakburn senior and junior (each in their turn mayors of York), and among the wealthiest inhabitants of the city in the first decades of the fifteenth century. Their affiliation with All Saints North Street is well known, thanks to the spectacular survival of a stained glass window clearly portraying their patronage. But it is important not to be blinded by spectacular survivals or misled into considering them to be either unique, or necessarily typical.
In 1432 Nicholas senior wished to be buried in York Minster and was the patron of hospitals and chantries on Foss Bridge and Ouse Bridge and in the two Micklegate churches of St John and St Martin. He was a friend of Dominican friars (also based off Micklegate) as well as a tenant of land belonging to Holy Trinity Priory next to the chapel of St James on the Mount. Blakburn was thus a typical wealthy parishioner of his time, patronising good causes and cults across a large number of religious institutions and not feeling restricted to the services of just one.
He was also one of the earliest recorded members of the fraternity of Corpus Christi based in the church of Holy Trinity to which he made a substantial bequest of £15. It is the flourishing of this major guild, which emphasises the importance, even in a large city such as York, of connections between and across lay church communities that survived and even flourished after the establishment of the parochial system.