The two factories in York were in fact quite close to Manchester. Slaithwaite and Marsden are small towns between Huddersfield and Manchester. In Yorkshire but 'no but a cock stride away' from Manchester.
Great site Christopher, good for trying to hunt early Irish in Manchester too, suggest you post this too on the Ireland general site if that is possible ? It looks as if it covered many Irish names as well as Mancunians.
Took a long time to extract relevant names but I have just finished searching and extracting to try and match with the 1841 census.