Could someone enlighten me what "pork belly politics is"
In this context, it would apply if Blackpool was electrified because its MP (Paul Maynard, Blackpool North and Cleveleys) happens to be Rail Minister.
It wasn't, the decision was taken by a Labour DfT (2009) and confirmed by the Con-Lib coalition (2011) before Maynard was appointed.
Similarly, I don't believe it is getting preference so that Virgin can run Euston-Blackpool (suggested upthread).
The Blackpool project was in gestation for a long time, but seems to have benefitted on the ground as a result.
In fact it followed the model that Mark Carne now prefers - do your detailed planning before sending the diggers in.
The Bolton project has been going for something like 3 years on site, and has had several setbacks.
Hendy cut the overall CP5 project funding which was probably why Stalybridge was cut, but NR was not in a position to complete it anyway.
The whole project might have been impacted by resources diverting to bail out the GW scheme, which is much more political.