Of all of the episodes, this was considered to be the funniest of the scripts, and after watching the hilarious stop-motion with the cows walking down the track, and Herbert's terrified expression, it's not difficult to see why!

Straight away, there is a noticeable difference in the quality of the film. The episode is slightly worse in picture quality than the previous three episodes, which were all filmed on a borrowed 35mm film camera. This episode was filmed using a digital camcorder, and while the quality is slightly worse, the turn around time for making this episode was much, much shorter. In fact, it was so much easier to make this way, that only Episode Five was then filmed using the 35mm film camera: every episode since has used the same digital camcorder (and thanks to editing software and much practice, the quality of the film for each episode has got better).

This episode was a lot more historical than previous episodes. Rather than commenting generally on how a railway works (such as the references to the goods trains in Veto a V2!), the very real and imposing figure of the London and North Eastern Railway's late lamented chief engineer, Sir Nigel Gresley, and some background knowledge to his designs is given. This also directly explains the reasons behind Herbert's and Nigel's names: Herbert Nigel Gresley is the CME's real name.

This episode saw a Britannia pacific locomotive used for the first time. This model would later form the basis of Stewart, the ???Clan??? class standard 6MT that first appeared in a non-speaking role in Episode Eleven. Not only that, but a clue as to things to come in Episodes Five and Six appear: Stephen appears incredibly briefly in his non-authentic express passenger blue livery.

The shots of Herbert in the tunnel with the cows was one of the best scenes in the series, and this episode has always been popular with the fans on Youtube. It is also a personal favourite of mine, learning new techniques for filming the cows was an interesting experience and what ultimately led to my fondness for stop motion animation (but not, sadly, improving my prowess at the latter!)