The eight-bay aisled nave has no western towers; the aisles are covered by quadripartite vaults. There is no transept but the transition from nave to choir is marked by flanking towers; the chevet has a single straight bay linked with a five-segment hemicycle surrounded by ambulatory and no chapels (like Notre-Dame of Paris).
The choir has a three-story elevation: cylindrical supports, a triforium that looks like a gallery and simple lancet windows in the the clerestory. West of this the tower bay has two stories (no clerestory) with skinny double columns in the arcade and a sexpartite vault. There is a spacious gallery on the north side. In the nave there is an alternating sustem of supports (intended sexpartite vaults?) and a glazed triforium like the nave of S-Denis and S-Séverin: the clerestory and the high vault were never completed. The aisles with their quadripartite vaults have enormous buttresses, clearly intended to launch flyers which were never undertaken.
This was a rich pays with a merovingian palace at Garges-lès-Gonesse and with woollen textile production. A priory was established at Gonesse by the monks of S-Florent-de-Saumur and endowed with substantial possessions in the surrounding area; the noble family of Montmorency appears to have also provided support.
The construction of the church was an ambitious project begun c 1190 perhaps with the support of King Philip Augustus who was born and baptized at Gonesse and who periodically resided there.
Work began on the choir modelled upon Notre-Dame of Paris almost half a century after that prototype-- towards 1200. Funds, ample at first, appeart to have diminished sharply by the mid-thirteenth century when the nave was undertaken. Here we find signs of changes of intention, abandonment of the upper story and vaults, and references to the nave of S-Denis.
Bottineau-Fuchs, Y., Haute-Normandie gothique, Paris, 2001, 215-221.
Catholic Church, L'Office des Saints Gervais et Protais, martyrs, patrons de Gisors, Gisors, 1835
Cheron, P.; Hérold, M.; Leroy, T., Gisors: église paroissiale Saint-Gervais Paint-Protais: les verrières, Rouen, 1993
Dubreuil, G., Essai historique sur Gisors