Workington is in the ward of Allerdale above Derwent (i.e. Allerdale S of the Derwent River), also called Copeland. Only the lower part of the W tower of the church remains in place from the medieval church structure, as most of the building was rebuilt in 1770. Two subsequent fires, in 1887 and 1994, led to the church being rebuilt two more times. The upper storeys of the W tower were built about 1770 and the nave after the 1887 fire. Following the 1994 fire, excavations were carried out which revealed much of the medieval ground plan of the church, which appears originally to have been a three-cell structure. A rough drawing of the church made about 1770 shows the medieval church before it was rebuilt. The bowl of the 12thc. baptismal font survives, as do parts of the W tower arch and a single, large scallop capital. Embedded in the walls of the church are various carved stones, including chevroned pieces. Loose stones of a range of dates, found over many years and during the excavations, are also kept inside the church. Although much of the interior of the church was destroyed in the 1994 fire, the 1880s exterior walls survive.

It is clear from stones carved in the 8th-11thc. which have been found at various times and in excavations of the 1990s that the site of St Michael’s had been an ecclesiastical one long before the first mention of the church. Unusually, the names of most of the rectors of the church at Workington from the 12thc. and later are known. The earliest documented, probably about 1150, was named Walter, who was named presbitero de Wirkington. He, alongside Osbert his chaplain (capellanus eius) and Acca prefecto de Wirkinton, witnessed a charter of Gospatric son of Orm confirming the gift of the church of Workington to St Bees Priory and the monks of York (St Bees was a cell of St Mary's Abbey, York) (Reg. of St Bees, no. 34). This was again confirmed by Thomas son of Gospatric of Workington. One of the witnesses in this document was Thomas chaplain (cappelano) of Workington (Reg. of St Bees, no. 35). Thomas also witnessed a later deed of 1184, where he is titled parson (persona) (Iredale, p. 136). Archbishop Roger de Pont l'Eveque of York (1154-1181) also confirmed to St Bees the church of Workington, along with other possessions. It has been suggested that the church of Workington may have been first given to St Mary’s Abbey in York before the foundation of the priory of St Bees in the 1120s, but this is not at all certain. Chetell son of Eldred first gave the church at Workington to St Mary's Abbey, York (Reg. of Wetherhal, no. 235) and Gilbert (d. 1220), son of Reinfredi, confirmed this (Reg. of Wetherhal, no. 209). In the confirmation charter of William Meschin's son Ranulf, however, it is stated that the church had been given to both St Mary's and St Bees, which Chetell son of Eldred had given (quicquid Chetellus filius Heltredi dedit in Wirchintuna, Reg. of St Bees, no. 4). This has led to some confusion. Workington had been given to or inherited by Chetell (or Ketel), son of Eldred. However, Chetell was still alive in the early 1120s. Later, William de Lancaster, baron of Kendal, exchanged Workington with Gospatrc son of Orme, who disappears from documents after about 1179. Gospatic's son Thomas then inheriited Workington. Following the Reformation, King Henry VIII gave the advowson of the church to Robert Brockley and John Dyer. They sold it in the same year to John Dalston, who in 1563/4 sold the advowson and patronage of the church to Henry Curwen.

No Domesday Survey was carried out for this part of England. Early references to Workington's church show that it's dedicatiion during the medieval period was to St Mary, though it is now dedicated to St Michael. In the period from 1136 to 1157 this part of England was under the control of the king of Scotland.

Thurlby (p. 277) suggests that the large scallop capital may have come from the chancel arch but is silent about the baptismal font. Pevsner thought it was Perp, but the carved work on the bowl of the font is so similar to the scallop capital that this is unlikely, a point noted by Hyde in the 2010 edition.

No evidence for buildings before the Romanesque period have ever been found, which may suggest that they were built of wood. Excavations carried out after the fire of 1994, however, revealed distinct phases of burials before the present church was built, the earliest grave dating to the 7thc. Differences of opinions for the dating of the lower W tower have still not been entirely resolved, dates of both the early-12thc. and late-12thc. having been proposed. Found in the excavations towards the base of the N wall of the tower is a stone carved with chevron, probably carved as a voussoir, which compares favourably with other 12thc. chevron voussoirs at the church (see: Zant and Parsons, p. 32).

Two stones found in excavations are carved with rough chevrons, lozenges and other decorative motifs. One of these was found in relationship to a child's grave, which radiocarbon dates to 995-1040 A.D. Comparisons with rough chevron found elsewhere in Cumberland (as at Crosscanonby) have been given suggested dates of the 11thc. (for example, The Corpus of Anglo-Saxon Stone Sculpture). The available evidence would appear to suggest a date in the 1st half of the 11thc. for the Workington stones (see: Zant and Parsons, p. 22 and pp. 75-6 nos. 10 and 11)

Although it has been written in some places that the first manor was built for the Curwens, it seems certain that the Workington family already had a house there by the end of the 12thc.

There has been considerable discussion about the relationships of the various parties involved, and it has long been noted that there is some confusion about the identities of certain people. G. Washington and M. Guido have both tried to unravel the complex connections.

Nicolson and Burn (p. 314), and Hutchinson (pp. 158-9 fn.) associate Chetell's gift of the church of Workington with Wetherhal Priory, but their source for stating this has not been found. It is clear that St Mary's Abbey, York was the recipient, as given in the various documents, including the Register of Wetherhal Priory. Whether the gift was made before or after St Bees was founded depends on the date of the document in which Chetell's gift is first recorded. Suggested dates vary from the late-11thc. to around 1120. The date when Gospatric took control of Workington and confirmed the church to St Bees is also undated. Gospatric son of Orm appears in various documents between about 1145 and 1179. Ranulf Meschin son of William Meschin, whose charter states the recipient as both St Mary's and St Bees, is thought to have died not long after his father (who probably died sometime between 1130 and 1135). Ranulf son of William Meschin had a sister Alice de Rumelly who inherited after his death (Reg. of Wetherhal, p. 9 fn. 5). The date of about 1150 which has been suggested elsewhere for Gospatic's charter seems not unlikely.