I think we've largely excluded the Spitfire from this discussion because it didn't see fighter service over France until Dunkirk. This discussion is "...up to Dunkirk...".
However, since I see the moment to educate and inform...here I go;
The Hawk-75A-4 or Mohawk.IV in British service was superior to the Spitfire Mk.I in everything but speed and armament. It carried six Browning .303cal instead of the Spitfire IAs eight. It only achieved 323 mph when the Spitfire I achieved 362 mph.
The Mohawk.IV was superior to the Hurricane also in everything but armament. The MOD seemed to under-estimate the Mohawks abilities and sent it off to the far corner of her empire, to Burma.
When the Mohawk became the P-40 Warhawk the speed increased that was so desired by the RAF and USAAF was achieved but at a large cost. Everything else on the plane was lost and the P-36 was left forgotten in the CBI.
The Hawk-75As were France's most successful plane during the French campaign. They scored Europe's first aerial victories on the 8th of September, 1939, shooting down two Bf-109Es.
The Hawk-75s over France were largely A-1s and A-2s. They had little A-3s and no A-4s. Had they possessed A-4s the story in the air might have been even more in the Mohawks favour than it already was.
The RAF took many of the deliveries sent to go to France. These were all A-4s and when retrofitted with RAF equipment were re-designated Hawk-75A-9s but were still called Mohawk.IVs.
With the FAF they scored 190 kills to eight air losses and six lost to AA.
http://curtisshawk75.bravepages.com/