http://www.youtube.com/watch?v=wvoENvK14N4

Like what I wrote in my review for Old Reliable Edward, UK users might not be able to watch it.

Ever wish to see Thomas's coaches, Annie and Clarabel, become a very central role in an episode? Last season, Brenner presented them as motherly figures in Thomas' Shortcut as they warn him of his carelessness along his branchline and worry along the way. On the morning of August 26, 2014 (British time), Thomas's most faithful coaches take part in Paul Larson and Laura Beaumont's first S18 collaboration: Not So Slow Coaches. In what is one of the five from the Trouble on the Tracks DVD, the two coaches are taken on an accidental adventure that carries plenty of emotional dialogue despite some realism screwups.

Strengths:

1. Once more, the characterizations remain in character. Everyone spoke the way they were supposed to.
    
   If you're familiar with Annie and Clarabel, they definitely sound like they love Thomas and are faithful to them, yet are extremely pessimistic with his speed. Their motherly tendencies badgered into Thomas, who was chugging down his branch line.
    
   Speaking of Thomas, if you're into him being extremely cheeky and not Mr. Goody-Goody Two Wheels, just like Old Reliable Edward, this is your episode. Each line drips with a lot of personality. The little tank engine acts as both an ally and foil to his coaches, as his reestablished immaturity rubs them the wrong way.
    
   Where their relationship is exhibited best occurs really early. As Annie and Clarabel complained about how fast Thomas was going, he decided to be a little cheeky…by crawling down the line. So when they told Thomas to speed up, Thomas accelerated, only to switch gears and have Thomas repeat his ol' tricks. The whole exchange is extremely clever of the crew and very in character of the trio. I'll get back to this in a bit.
    
   The other important characters in NSSC, Charlie and Catlin, are also in character. The Playful Purple Engine tells his corny jokes (as usual). Like Connor, Caitlin is proud of her ability to travel while remaining competitive.
   
2. Just because you're cheeky doesn't give you the incentive to not be hit with consequences, and they are abundant. Because Thomas played around on the rails, he learned how late he was to Dryaw. Then he had to hurry back to the Shunting Yard to arrive at the Ffarquhar Quarry (located at the end of his branch line, as reestablished in Thomas the Quarry Engine), which he did on time. Because his scheduling sucked, he arrived back too late to catch Caitlin, who pulled Annie and Clarabel across the island. That left him feeling very guilty for teasing them. Deservingly so, I might add.
    
   Of course, there's the slight, friendly ribbing at the end, so it isn't like it'll all go away.
   
3. The episode really exudes the fear of Annie and Clarabel racing down the mainline and Thomas not catching up to Caitlin. Two exchanges between the coaches is where it works so well:
    
   As Caitlin pulls away from the Shunting Yard:

   
   Clarabel: This…is the fastest…we've ever been!
    
   Annie: I don't like it…at allll!
    
   Clarabel: I've got my eyes closed!
    
   Annie: Does it help?
    
   Clarabel: No. Not really! *opens one eye and then the other, glancing nervously around her*

   And during the race with Connor:

   
   Annie: HEEELLLLLLLLP!!!!
    
   Clarabel: Clarabel: I'll never complain about Thomas again!
    
   Annie: Nor will I!

   Think about it. If you're a pair of really old coaches with the occasional need to be painted so you don't look like a "beach hut on wheels," you won't want to go fast. Not to mention it brings Annie and Clarabel's complaining of Thomas's speed in full circle.
    
   Kudos to Theresa Gallagher (also the voice of Mavis) for giving both characters the enthusiasm and emotion needed to drive this character-centric conflict.
   
4. If you're interested in the music, then Robert Hartshorne's musical scores work really well. His best is heard during the chase as his instruments reflect the desperation for Thomas to catch up before it's too late. Even better is how despite informing the audience of how frantic the situation is, it doesn't hammer everything in. When placed in the right context, it creates a more powerful message and doesn't make it so blunt that it tastes bitter or becomes cringeworthy to listen to.
   
5. One of the biggest problems with The Afternoon Tea Express (also penned by PL/LB) was by how much the narrator was relied on, telling the audience every single thing about the story, from the danger to the speed to expressed emotions. There was no silence or independence from Moraghan. Not here. With plenty of room to breathe, Moraghan is used only when necessary, making the story better than it should.
   
6. There's no clear moral to the story. When analyzing it to its simplest point, it follows the Fish Out of the Water trope, something this series has used a lot in the past, including the classics Thomas & Gordon/Thomas Gets Tricked and Wrong Road. You can't really locate the actual moral because it was placed so far on the back burner, instead focusing on the characters, action, and resolve.
   
7. In the whole eight-and-three-quarter-minute episode, the only characters to appear are Thomas, Annie and Clarabel, Caitlin, Charlie, Connor, and Hiro. No other member of the "Steam Team," Sir Topham Hatt, or any other engine showed up, allowing the conflict's development more flexibility.
   

Weaknesses:

1. The engines' animation isn't very refined. To see what I mean, look at this chart from Wikipedia:
    
   
    
   The numbers you see are all part of the Walschaerts Valve Gear. Most large engines on the Island of Sodor have this configuration, including Gordon and Henry. Caitlin's and Hiro's styles are a little bit different, but operate the same way nonetheless. If you want to know what the key numbered parts are, click here for the information.
    
   Take at look at Caitlin's left valve gear:
    
   
    
   See the light gray bolt on her second driving wheel? It remains stationary as her wheels rotate.
    
   Now look at her other side:
    
   
    
   Her entire valve gear remains in one spot.
    
   Later in the episode, Hiro also has this same problem with his missing fly crank (the piece connecting the side rods to the fly-crank rod).
    
   
   
2. There's some unnecessary exposition. To illustrate two examples (all underlined):
    

   
   Narrator: Meanwhile, Caitlin was pulling into the Shunting Yard. Caitlin was a very fast engine, indeed.

   
   Caitlin: I've been going so fast, I've loosened some bolts, Charlie. I need to go to the Steamworks to get them tightened.

   Because she's so streamlined, it's obvious she's going to be fast. By having the narrator tell the audience, you're repeating the point and thus minutely hammering in her speed.
    
   Also, don't tell your audience (both primary and periphery demographics) her bolts are loose. Show them via a close-up of a few loose bolts on her wheels. Differentiate which bolts are loose and tight by having a workman like a driver or fireman review her. Although this might be a bit picky, don't you think having a streamlined engine with loose bolts speeding down the main line would be dangerous? If they become looser, then they could fall of and cause more confusion on the island. Preferably, I would leave Caitlin in the Shunting Yard, call in Rocky or the Breakdown Train to pick her and her tender up (who to tow? I'd choose Edward, Henry, or James because of their agility), and travel to the Steamworks altogether.
   
3. Once more, Charlie tells a really dumb joke.

   
   How do bees get to school? On a school buzz.

   But this is not where the comedy fails.
    
   What makes it miss the mark is by having both Charlie and Caitlin laugh at it, although Caitlin less so because of her chuckle. If Charlie found it funny and Caitlin not, then the joke might work because she could display a facial expression (maybe a sigh and/or eyeroll) that would reflect back at the audience, especially the older ones. No, Hartshorne's stylized "womp-womp" is way too subtle to get the joke across.
    
   Besides, wouldn't it be more sensible if Charlie told a much better joke? That way, Charlie's screwup won't feel so forced. He's capable of doing more than just tell awful jokes that merely pander to kids, as shown by Not Now, Charlie! and his cameo in Toad's Adventure. Sure, it'd still be contrived because his driver apparently allowed this to happen, but you'd at least correct half the mistake by not flanderizing him.
    
   Speaking of Charlie, after screwing up his job, he wasn't seen again. No signs of regret. No apology. No consequences. No nothing. Sure, it was portrayed as something he did wrong because it was an accident, but show him feeling remorseful for what he did. Don't force both kids and their guardians to create headcanon to resolve the plothole.
   
4. As presented, the whole chase scene is implausible. From the second half onward, Thomas attempts to chase down Caitlin to retrieve Annie and Clarabel, who were towed along the ride. The whole goose chase kept on going until Hiro stopped Caitlin offscreen while she was on the Mainland. Instead of having Thomas chase Caitlin around the island, why not have him and/or Charlie race to the nearest signalbox and telephone instead? That way, traffic down the mainline can be halted as Caitlin is forced to stop at a subsequent red/danger signal. Then you can have someone — hell, maybe Thomas himself — retrieve his coaches and resolve the error. Or like what SkarloeyRailway01 wrote in his short review, have Thomas's driver alert the signalbox down the line, only to miss the warning as Caitlin races Connor. Having these little details would make the predicament much more plausible. While the chase is pure adrenaline and fun, it plods the pace, making the journey feel empty instead.
   

During Series 17, the most controversial writer of the season was the team of Paul Larson and Laura Beaumont: They can write really well, write average, or write poorly. The Afternoon Tea Express was easily one of S17's worst. Not So Slow Coaches is one such episode that helps them maneuver back on the right track instead. With on-point characterization, plenty of stakes, a lack of obvious moral, and a good dose of karma, it's an episode that deserves some accolades. Yet, some obvious contrivances merely hold NSSC back from being one of its greats. Overall, a decent episode.