So, the plot thickens.
I've found another of the Monk/Monkton brothers - a Joseph Monkton, born 1816 in Rock, Worcestershire (again, listed as Monk at birth, son of William and Elizabeth).
He marries a Sarah Maxfield of Beckbury, Shropshire in the village church in Pattingham in 1836. They have two children - George Monkton, born 1837 in Wolverhampton and Thomas Monkton born in 1839 in Pattingham.
Something then happens in between, because Sarah Monkton then marries a George Hamlett in 1841. I can't find her in the 1841 census but she's present in the 1851, living in Sedgley. She's listed as Sarah Hamlett alongside her son Thomas, listed as Son-in-Law to her husband George. I assume Joseph died, but I'm not sure. There's someone I believe to be a Joseph Monkton of around the right age living not far away in Willenhall, Staffordshire in the 1841 census, but I've yet to confirm that.
There's also another Monkton living in Pattingham in 1841, a James Monkton, living with his wife Sarah and son Thomas. He's about 50, and interestingly is listed as having been born in the county, so not a Rock child.
This is proving to be one hell of a knot to untangle, but I'm growing more convinced that this family's history is tied very strongly to the Staffordshire-Worcester canal. It geographically links what would otherwise be a very disparate series of moves and relocations.