On the other hand, American pronounce the same vowel as British do & they stress the same syllable in a particular word, as the American/Australian/Indian themselves, since the "stress" pattern in a particular word is to do with the "English language" itself & not with the individual accent. Afterall, word like "heart" has LONG "a" vowel, which is pronounced by ANY English speaker, regardless of their accent.
I rather see the "vowel" (and consonants, course) articulation i.e the sound articulation itself, as a factor that distinguish between accent.