I think it's often interesting to learn the history of people's names. And for the people in the stories on this site, it's especially true. Many of them still carry the names of places practically within walking distance of Leigh. Surnames had been in widespread use for many hundreds of years by the time these folks were living, so when you see a name like that it seems reasonable to imagine the person's ancestors had lived in the area for 10 or 20 generations or more.
Gallagher is a very old Irish clan name from County Donegal, the northernmost county in the Republic of Ireland. It goes back 1000 years to the clan founder Gallchobhair mac Rorcan (wikipedia). The modern Irish version is Ó Gallachóir.
The Anglicized form Gallagher is apparently pronounced goll-a-her in County Donegal, and gal-a-her elsewhere in Ireland. In Britain and the US it's usually pronounced gal-a-ger, with a hard G sound.
In Old Irish the name has the elements gall (foreign) + chobhair (support). The word gall also forms the last portion of the county name Donegal.
Gallagher is very popular in the province of Ulster (where Donegal is) and Connaught (popularity).
Farrington derives from the township of Farington in Lancashire (map, wikipedia), about 20 miles north of Leigh. Etymologically it's an Old English name. The -ton suffix refers to a farm or settlement, and -ing often refers to "the people of" (wikipedia). Others suggest Farington means "the place where ferns grow."
The name Farrington is recorded in English records as early as the 1300s, and only shortly afterward in Ireland as well. Today it has a similar frequency of occurrence in both places. In Ireland it mostly occurs in Leinster province (e.g. Dublin), and in England it remains most common in the historic Lancashire county.
Lomas is another name derived from a place in Lancashire. The place was originally called Lumhalgh, but it no longer exists. Its precise location is no longer clear, but it was just east of Bury, and you can still find roads and areas referring to Lomax there (map). It's about 16 miles northeast of Leigh.
The name Lumhalgh is Old English, with elements lumm (pool) + halh (recess). The modern names Lomas, Lomax, Loomis and other variants all derive from this place. The forms Lomas and Lomax were used almost interchangeably, even within individual families (history).
Baxter simply means baker. Part of the difference between Baxter and Baker is that the former derives from the feminine form of the word.
Page is also occupational, coming from the "personal attendant" sense of the word. That sense may ultimately derive from Latin pagus, a rustic or villager, much like the word pagan (etymology).
Battersby is another place name, in this case a township in the North Riding of Yorkshire. It's quite far from the Leigh area, but only a few miles from Whitby, where Dracula landed. The -by suffix comes from Old Norse, and like the Old English -ton it indicates some sort of settlement. Today the name Battersby is more frequently seen in the Leigh area than it is in its native North Yorkshire.
Marlow comes from the name of a town in Buckinghamshire, nowhere near Leigh. Etymologically it refers to the place were a lake used to be, from mere "lake" + lafe "remnants, leavings".