(15 May 2015, 6:48 am)MurdnunoC wrote I'm going to guess 'the hole' is beyond the termini of the 156.
So, in the scan above, the hole would be the bit where the 157 loops around Barnwell?
On that map, it is where the 157 is, just above the E in Penshaw.
The road narrows, to a very narrow road. Very tight turn at the top, before going through Penshaw village. It is then single track again, as it goes down the hill - before widening out again.