Since all Bentleys had coachbuilt bodies, and there were various wheelbases, to say nothing of specials, such details as height of headlight, number of louvres, and so on are pretty meaningless.
You can tell it's a tall radiator car, but that could mean either a 6 1/2 litre or 8 litre. If 6 1/2, might or might not be Speed 6.