I had a look at some of the John Whitesides who were in Poulton late 18th/early 19th centuries.
John Whiteside, shoemaker & wife Peggy/Margaret, married 1788, had at least 6 children. They were still living in Poulton in 1841, both aged 70. Some of their family were shoemakers.
Neighbour James Whiteside (60) was also a shoemaker.
John Whiteside, shoemaker & Isabella were also still in Poulton in 1841; he was 65 with a houseful of children.
Nearby John & Isabella were a younger John & Isabella (40 & 35). He was also a shoemaker and his teenage son an apprentice shoemaker.
3 neighbours of the 2 John & Isabella couples were also shoemakers.
So, none of the above John Whitesides could have been the same John Whiteside in an earlier life as the John who was at Salmesbury in 1841. I was trying to trace and eliminate some possible candidates.
John Whiteside who married Jane Salthouse:
Marriage 1798. John was a husbandman (agricultural labourer).
5 children, all baptised at St. Chad, Poulton. Henry 1799, (died 1808); John 1801; Robert 1802; Samuel 1805; Thomas 1807. Abode for all was Highfalong (?). The father's occupation was farmer at baptism of John 1801 and Thomas 1807. ( I forgot to note occupations at other baptisms.)
Burial Nov. 1807, St. Chad, Poulton, Jane Whiteside, aged 42, wife of ----, abode Highfalong, occupation farmer.
John Whitehouse, widower married Betty Rimmer 1808.
(Jenny Whiteside, natural daughter of a Betty Whiteside, abode Carleton, was born Sep. 1812 and baptised at St. Chad in October. I've explained in my previous post why I consider Jenny was not the child of Betty (Rimmer) Whiteside. She should therefore be ruled out of this enquiry IMO.)
I tried to trace the 4 surviving sons of John & Jane Whiteside. There was a marriage of a Samuel 1829. He was a miller, abode Kirkham. Marriage bond gave abode as Singleton (I think, didn't write it down, running out of paper.) His bride was from Poulton. This may have been a different Samuel.
Eldest surviving son of John & Jane, John junior seems to be a farmer at Highfurlong in 1841. He was aged 40 and was a single-person household. In a separate household in same building were 2 teenage boys who were ag. labs. + 2 female servants. Were these all his servants? As he seemed to be running the farm, what has happened to his father, the elder John and his stepmother, Betty, if still alive? One would expect them still to be resident in the farmhouse or a cottage nearby. Most farmers don't give up the reins easily, even when the son & heir is middle-aged.
I couldn't identify Robert b. 1802.
Possible candidate for Thomas was an innkeeper in Wigan in 1841 but he's doubtful.
There was a 1799 burial of Henry Whiteside (80), yeoman, of Highfalong. Seems like John senior took over the farm on Henry's death. Henry and one or both Johns may have made wills. Other records to look at/for are leases and Tithe records.
It seems very unlikely that John Whiteside Senior, a yeoman farmer, would give it up for the life of a shoemaker. I've got both occupations in my tree. My yeoman farmers were comfortably off, well respected in the community, sons became farmers, land agents, corn-dealers/millers, innkeepers; daughters married other farmer, millers, maltsters, businessmen, doctors. Shoemakers learned their trade as boys, often from their father. There was a saying "The shoemaker's children go barefoot" i.e. a shoemaker couldn't afford to spare leather to make shoes for his own family, or worked such long hours he had no time to make them. A few shoemakers with larger workshops in towns where there was a wealthier customer-base were successful.
To conclude. I agree with other posters/researchers. Evidence and logic strongly suggest that John Whiteside, shoemaker, father of Richard, who was at Salmesbury Mills in 1841 and died there 1842, was not the same John Whiteside, husbandman, later farmer, who married Jane Salthouse there in 1798. Betty Rimmer, who married a widowed John Whitehouse in Poulton 1808 was not the same Betty from Devon who married John the shoemaker and gave birth to Richard in 1815 in Dublin.
BTW Rimmer was another locally common surname.