This is struggling in full sun, although I have some thriving in full shade. Interesting listing can be found at http://www.aujardin.info/plantes/campanula_muralis.php .
Easy and reliable
Early June, zone 5a, Allen Centennial Garden, UW-Madison
Grows in Quebec, Canada, Zone 5b
From the Monterey Bay Nurseries site...I *believe* "Blue Gown" is a cultivar of the C portenschlagiana
In Susan\'s garden in Auckland, NZ