When we first met Colin, him and Freddie were helping out at the Wharf. Freddie decided to plan a party for him at the Wharf, but Colin kept explaining to Freddie they never had parties at the Wharf before but Freddie took no avail and huffed out of the Wharf.
Freddie brought all of the party surprises to the Wharf. He asked two engines about the party and huffed into the Wharf with the surprises, suddenly, a bargeman took the surprises and Freddie blew his whistle so the bargeman would come back.
"Fearless" Freddie told Mr. Percival about the party, Mr. Percival told Freddie he should of asked him first before getting the surprises. However, Freddie soon put the surprises there soon.
Soon, the party started, Thomas and the other narrow gauge engines were invited, Colin thought it was a wonderful party, he enjoyed it and Colin was (at the party) the guest of honor!
Colin is a cheery green crane working at the Wharf. He is currently friends with "Fearless" Freddie and works hard and proves to be Really Useful.
Colin is based on a green wharf crane. However the specific basis is unknown.