Thomas was a mining engineer and mine owner in Cumberland County, England. He sold his interest in the Gillhead Colliery near Maryport and came to Colorado to start a new one. (From the maps that whole area of Cumberland is honeycombed with old mines. They even mined off at an angle and went under the sea).
(Speaking of family stories - when I first got started there were only dim memories of it. In family lore Thomas and David got combined into one person ; and the mine "he" owned was, what else but, a gold mine ! It was, there and here, coal mines)
I guess they wanted to make sure it was worth it and that's why they left them behind. I've found Thomas and David on the 1880 census. I can't find the women on the 1880 U.S. Federal census nor on the 1881 U.K. census. Also Thomas and Jane (McClean) Carlton's daughter came along and was married in Louisville on 6 Nov 1881. So they arrived sometime between c.Summer of 1880 and Nov. 1881.
David's wife, Jane Trimble, his mother, sister and 5 girls stayed with Aunt Bella, Jane Trimbles sister, in Carlisle, Cumberland.
Like they say "the devils in the detail" , hard to find but it makes them "people" for me.