It was first enfranchised in 1558 (though the Parliament so summoned did not meet until the following year), and was a rotten borough from its inception: Newton was barely more than a village even at this stage, and so entirely dominated by the local landowner that its first return of members described it bluntly as "the borough of Sir Thomas Langton, knight, baron of Newton within his Fee of Markerfylde".

In practice, however, the townsmen of Newton had no say in choosing their representatives: as the owners of the majority of the qualifying freeholds, the lords of the manor exercised total control.

During most of the Elizabethan period, Langton seems to have allowed the Duchy of Lancaster to nominate many of the members, which may have been a quid pro quo for Newton's being enfranchised in the first place, but later patrons could regard its parliamentary seats as their personal property.

By the time of the Reform Act 1832, Newton was one of the most notorious of all England's pocket boroughs, mainly because the Legh control was more complete than that of the patrons in most other constituencies.

The Redistribution of Seats Act 1885 created a new Newton constituency, as one of twenty-three divisions of the parliamentary county of Lancashire.

The constituency, officially designated as South-West Lancashire, Newton Division consisted of a number of townships and parishes around Newton le Willows namely: The electorate also included the freeholders of the municipal boroughs of St Helens and Warrington who were entitled to vote in the county.