Alfie Has a Secret is a cancelled episode of Jack and the Sodor Construction Company.
A new school crossing is being built. Jack is surprised to see Alfie at the site, after all, they do not need any trenches dug. Alfie will not tell Jack or Isobella what his job is. As the day progresses, Jack and Isobella watch Alfie drilling and then digging a trench across the road. Alfie then lays a pipe in the trench and puts up a small sign with a picture of a hedgehog on it.
Alfie had been building a crossing for the hedgehogs while Jack and Isobella had made one for the children. Now everyone can cross the road safely.