Culdee Fell Railway Adventures was a mini-series that was planned along with Small Railway Adventures, but it never went into production and was therefore dropped.
The series would've probably aired in late 2012, if it hadn't been for the tight schedule that moved a lot of specials out of 2012, but it was probably to air after Small Railway Adventures (late 2013).
Nearing the end of 2012, it was taken away from Adventures on Rails's mini-series list. It was confirmed in January 2013, that it had been cancelled due to lack of ideas. It can also be commented that Adventures on Rails had also rebranded and the fiftth season was no longer canon. Another rumour is that airing time probably set it aside until it was decided it would no longer go into production. On November 24th, 2013, welll over a year since its creation, writer for AOR, MainLineEngines comments:
"The series was cancelled due to lack of ideas and interest. We made the first episode, and went blank; we brainstormed, but we just couldn't. We suffered the same as the Reverend. Eventually, I asked my helpers if they wanted to continue. I recieved a no. We decided to instead focus on Dark Days of Thomas the Tank Engine and Small Railway Adventures instead."
- The episode from Small Railway Adventures, Two Unusual Railways is rumoured to be a hint about the "lost" mini-series.
- It is also rumoured that perhaps the "rebranding" on Adventures on Rails would be another reason for the series' extinction. Thus, the fifth season would no longer be canon.