Thomas and the Billboard - S12.E1

It's Knapford Station's birthday and all the engines are preparing for the festivities. When a photographer comes to photograph the engines for a billboard Diesel accidentally obscures Thomas; Thomas thinks this was on purpose and is so distracted he goes the wrong way and knocks the billboard over. This gives an opportunity for all the engines to be in a new photo, but when Diesel isn't told, he has to do all the others' jobs. Everything is soon rectified and the new photo is put up at Knapford.