I have been researching QUALTROUGHs world-wide for almost 30 years.
The name originates from the Isle of Man, however I have found Qualtroughs & descendants in most western countries around the world and in some other interesting places also.
Variants include... Qualtraugh, Qualtherough, Qualter/s (not all as most originate in Ireland), Qualtrop, Calthorp (in Devon) Coltrough, although most of these variants refer to useage in the 1700s mainly.
A website for this family name can be found at
http://www.qualtrough.org This site includes scanned images of the book on the family I co-wrote in New Zealand in 1984 called "A QUOTA OF QUALTROUGHS - Early settlers for New Zealand from the Isle of Man" There are also 3 other subsites, including updated lineages since the above book was published, and a resource of Qualtrough references from all over the world.
Anyone interested in or connected to this name please contact me. Thank you.
Elizabeth