I too have John Wall 1621 on my tree, but have failed to find any more about Troth. I have traced some earlier generations starting with Richard Wall 1515- 1548 and his wife Clements Birke. However it is some years since I looked at this line so am not confident that they are correct. I have the Darley PR's on disc so will need to review my evidence.
I am descended through Sarah Wall (1761) marrying Richard Milner (1764)
I would be interested if you manage to turn anything up on Troth!
Ruth