Lt Harald Gebhardt VS claims

[Laurent Rizzotti]

According to JG 26 story by Don Caldwell, I./JG 2 first intercepted a RAF raid on Caen airfield, then joined other German units later to attack US bombers returning from a raid on Paris suburbs.

German claims of this day seems to confirm the hour difference:
_ 2./JG 2 claimed 2 Spitfires N Cherbourg shortly after 1000 hrs (vs 504 Sqn Spitfires on ASR escort, 1 shot down, 1 damaged)
_ 3./JG 27, 2./JG 2 and 11./JG 2 claimed 4 Spitfires N Caen between 1328 and 1341 hrs (against RAF 11 Group Ramrod 51/II, RAF 2 Group on Carpiquet airfield, 2 Spitfires shot down)
_ JG 2 and JG 26 pilots claimed 4 B-17s and 9 Spitfires between 1430 and 1500 hrs between Rouen and over the Channel (against US bombers and RAF escorts, 4 B-17s and 7 Spitfires lost)

So I would say that Mathews/Foreman are probably wrong.

As for the location "SW Grün du Breuil", I think it is a badly written form of "St Ouen du Breuil", a village exactly north of Rouen.

According to https://francecrashes39-45.net/rech_avion.php all seven Spitfires fell in the area north of Rouen. One claim by Lt Hoppe of 5./JG 26 was made over the Channel and is so overclaim, leaving 8 claims for 7 losses between Rouen and Dieppe, not a bad score.