Ashton-in-Makerfield, or in the Willows, as it was variously called, was the largest and most populous of the townships in the ancient Parish of Winwick, and would originally have been included in the Diocese of York.

About the beginning of the tenth century, the land between the Ribble and the Mersey was transferred to the Diocese of Lichfield then in 1541 to the new Diocese of Chester. In 1880 the Diocese of Liverpool was created out of Chester, and Ashton has been in the Diocese of Liverpool since that date. From Medieval times Ashton formed part of the Rural Deanery of Warrington, but since1865 has been in the Rural Deanery of Wigan.

In 1845 The Winwick Rectory Act was passed dividing the old Parish of Winwick into ten new Parishes-Winwick, Croft, Cultcheth, Newton-in-Makerfield Emmanuel, Newton St Peter, Newchurch, Golborne, Lowton, Ashton-in-Makerfield, and Ashton St Thomas. It was enacted that the Parish and Rectory of Ashton-in-Makerfield should comprise the whole of the township of Ashton-in-Makerfield "except that part which is called the Town End", and that the Town End, together with the whole of the township of Haydock should form the Parish and Vicarage of St Thomas.

The Town End was defined as "all such parts of the township of Ashton-in-Makerfield as shall be to the southward of a line to be drawn as follows: beginning at a place where the boundary between the township of Ashton-in-Makerfield and the township of Haydock crosses Millfield Lane, and thence along the centre of the said lane to a certain other lane called Dock Lane, thence Eastwardly along the centre of such lane to a brook which crosses the same lane about 65 yards beyond the fourth milestone from St Helens thence crossing the same lane to the north- easterly abutment of a bridge which crosses the said brook; thence in a straight direction to a mere stone, standing in Nichol Lane near the place where a public footway enters the same lane; thence along the centre of Nichol Lane to Long Lane and thence along the centre of Long Lane to Old Bryn Lane; thence along centre of such lane to a place where Coffin Lane Brook crosses the same lane and thence following the line of the brook in an easterly direction until it reaches the boundary of the township of Ashton-in-Makerfield."

The Parish remained as such until in 1869 the Parish of St James Haydock was formed, taking over from St. Thomas's the whole of the Township of Haydock except that part which lies eastward of a line drawn down the centre of Kenyon's Lane, Penny Lane and Vista Road.

The Parish boundaries were revised again on the 25th of August 1931 when parts of the Parishes of Ashton-in-Makerfield (Holy Trinity) and parts of St Thomas's were formed into a "Consolidated Chapelry" and assigned to the Church of St. Peter’s Bryn.

In 1935 a further boundary adjustment conferred part of St. Thomas's Parish in the Township of Haydock to the Parish of St James. The last boundary adjustment in 1980 left the Parish boundaries as follows:- beginning at the boundary between Ashton and Haydock at Millfield Lane, then along the centre of Millfield Lane to Liverpool Road, eastwardly along the centre of Liverpool Road to the M6 Motorway, northwards along the M6 to Lowbank Road, then eastwards along the centre of Lowbank Road, Cansfield Grove and Alexandra Road to Bryn Road South, north along the centre of Bryn Road South to Bryn Rd, along the centre of Bryn Road to Lockett Road and then in a north easterly direction to Old Bryn Lane, then in a south easterly direction to Coffin Lane, eastwardly across Bolton Road to Coffin Lane Brook, following the brook eastwardly to the boundary of Ashton-in-Makerfield; following the boundary south and continuing south to the East Lancashire Road, west along this road to Kilbuck Lane in Haydock, following Kilbuck Lane until it joins Millfield Lane and then back along the boundary with Ashton.