Does anyone know of any diagrams that are reliably a 156 outside of the Barton branch?
Depends on the day of the week, but as the post above says they are mainly in Lincolnshire.
Monday - Friday the first train in the morning from Lincoln - Cleethorpes is always a 156. But it is a position move for the Barton service.
The daigram with the 0552 Cleethorpes - Newark is one that you have a good chance to see a 156 but it can be anything as can the 0730 Grimsby Town - Leicester.
Saturday apart from the Barton positioning move I don’t recall seeing a 156 on a regular diagram.
On Sunday many of the trains to in the afternoon are 156.
The 1530 Nottingham - Cleethorpes swaps with the Barton service
The return service at about 1830 is the Barton Branch 156
The last train in the evening from Cleethorpes - Lincoln is also a 156