Once again, The Railway Series draws inspiration from the real world, this time in the form of a real life locomotive, Wilbert, named after the author's father, and from a class of school children, who provided the author with the first story - Percy's Poriddge!  This book was also due to be the build up to the originally intended Book 39, which was overturned by the Publishers, but more on that next!

Percy's Porridge

When Donald and Douglas need help, the Fat Controller turns to a friend of his in Gloucestershire who can help.  The friend took him to see Wilbert, a saddle tank engine who works on the Dean Forest Railway.  The Fat Controller intends to use Wilbert to conduct tests and then buy a similar engine to help out on his railway.
Percy is disappointed however when he finds out that Wilbert will be helping Duck instead of coming to Thomas's Branch Line.  But the week before he arrives, bad weather sets in and it rains terribly.  On one particular day, Percy is setting out from the station when several bags of oatmeal topple over and land on the track.  Percy runs into them and is covered in porridge.  As a result, Percy needs to be taken to the Works, and Wilbert is put to work on Thomas's branch line in his place after all!

Cab Over Wheels

Wilbert tells Toby and Thomas about the Dean Forest Railway.  Since his first job is due to be in the Lead Mine, Thomas warns Wilbert to be wary of the DANGER sign.  But Wilbert tells Thomas he knows what he's doing, and that he's had experience of an engine who ran past a Danger sign too!
Wilbert tells them the story of Sixteen, an engine who's job was to move trucks to the same place every day, a job the engine got sick and tired of.  That and his curiosity was bothering him, he wanted to know what lay beyond the Danger sign.  He seized his chance on a wet day when the rails were slippery and the trucks could pull him forward.
Sixteen blames the incident on the trucks, and he ends up on an unsafe embankment.  When the Driver is ordered to the office by a Foreman, and the Fireman is told to move Sixteen back, disaster strikes.  The rails beneath Sixteen sagged and he topples over, landing on his side and leaking steam everywhere!
After that, according to Wilbert, he was rescued and sent to the back of the shed in disgrace, but got better than he deserved and got a very lucky second chance by a preservation group in the Midlands who restored him again.

Foaming At The Funnel

Wilbert is sent to take Percy's milk train from the Dairy, so far he has proved to work well with trucks after he takes the stone trucks to the Harbour.  After doing a delivery, Wilbert ends up chatting to James as he goes about his work at the Junction, and hence they forget to fill up with water when they're at the station, so instead, they decide to take on water at the Dairy.
However, the Fireman puts in the wrong hose and begins filling the tank with milk instead of water!  Thomas brings him back to the shed, and Wilbert's tank is cleared out and he's washed.  Thomas jokes - "Percy got the porridge, you got the milk!"

 
Wired Up

Percy returns from the Works, and Wilbert is told he will be going to work on Duck's Branch Line instead.  Duck and Oliver give him a kind welcome, and Duck allows him to head his next train to get a view of the route.
The following day, when Wilbert is taking some ballast trucks, the truck loses it's coupling-gear and it's unable to be moved.  Wilbert's Driver spots a coil of wire close to the line and Wilbert suggests the possibility of pulling a truck with the wire.  Wilbert does so with ease and then moves the truck to the end of the train, and moves it on to the Big Station.
At the end of the visit, the Fat Controller realises an engine like Wilbert is just what he needs for his railway, and wishes Wilbert a warm goodbye as he sets off for home again!