The 1813 reference (Catalogus plantarum Horti Regii Neapolitani ad annum 1813) reports also the botanical origins of the plants listed. According to it, this rose was from Hortus Regius Casertanus.

However ... in the same catalogue are listed separately Rosa sempervirens. (n. 3798) origin: indigenous and Rosa scandens (n. 3796) origin Hortus Regius Casertanus. Not knowing much of the origin of these one-two roses I do not know if this latter information supports or invalidates the italian origin of Rosa alba regalis

Christopher Thompson of Pickhill, Yorkshire, names this rose ("La Royal") in his nursery list of 1783.
See "Some Old Roses" by John H. Harvey in The Rose Annual, 1976. page 95.