Trucks

"Cheeky chopper!"
Harold is returning from his inspection when he spots a little Diesel coming round the mountain. The Diesel is Rusty and despite his friendliness, Rusty has little time to chat and regards Harold as being cheeky.
Rusty's arrival pleases Sir Handel and Peter Sam, but Sir Handel remains his usual grumpy self. The trucks dislike Sir Handel and repeatedly play tricks on him, making him dislike working with them. Sir Handel is advised by Gordon that if he were ill, he could not shunt trucks.

Sir Handel takes the hint and, when he feigns an illness the next day, Peter Sam is allocated his trucks. He takes them to the slate mines and waits for his full ones, but the trucks mistake him for Sir Handel and brake their coupling, smashing into him and cracking his funnel and denting his boiler.

Rusty helps clear the mess and the Fat Controller reprimands Sir Handel for lying.

On the way home, Harold spots Rusty again. This time Rusty mimics Harold from their previous meeting and uses his phrase "cheers and keep up the good work"