Nigel the V3 tank engine was first introduced in the fourth episode, and had proved a mildly popular character. Therein lies the problem of a fairly substantial cast, to be able to fully appreciate all the cast members you have to have dedicated episodes to such characters. Episode 13 and 14 were all about the relationship between Nigel and Herbert: two engines linked, both by their names (Nigel and Herbert coming from Herbert Nigel Gresley, their designer) and by their at-odds personalities. Herbert sees Nigel as something of a hero, given the tank engine's exploits in his first episode (saving the hapless Herbert from a herd of cows!), and Episode 13 was a way of seeing Herbert trying to give something back to his friend and hero.

Further, it would prove to be a neat way of re-introducing the aspect of Copley Hill being a self contained, but by no means perfect yard. Nigel being shunted back into the shed caused some headaches, the old Lima J50 tank engine being old, worn and definitely on its last legs at the time of filming.

The shed scenes are something that haven't really been explored very much: seeing Nigel being repaired during the night gave some lovely, atmospheric shots that would continue with the filming of Episode 14.

Compared to other episodes of similar length (Episodes 7, 11 and 12), this episode doesn't particularly stand out despite the use of the snow covered set. It was meant to build up to a dramatic (and heart-retching) conclusion in Episode 14. In that sense it did its job: Nigel was ill, repaired temporarily, and put back into service. For how long, is another story...