I don't believe that this road has ever gone by the name "Chapel Down Lane End" from my own local knowledge and can only find this on modern maps.

There was a Chapel in Brownston historically and old OS maps show a note further towards Modbury with "Chapel Down Lane End" written, but this is written in a slightly random location and does not appear written as road name.

I would suggest that this road might be either called simply "Chapel Down Lane" or it could be a continuation of "Old Dartmouth Road".

I am not sure at what point the name "Old Dartmouth Road" should end as this isn't on many maps, but it might go via this route or the southern route that bypasses Brownston.