Tim was not featured in any stories, but was featured on the Rev. W. Awdry's layout of the railway. It is unknown what happened to him after the Mid Sodor Railway closed.
Tim was made out of a Gem Vari-kit, and does not appear to be based on any particular locomotive. He appears to have an 0-4-0 wheel arrangement behind his sideplates, and he has a large coal bunker placed above his tanks just in front of his cab.
Tim is painted black all over with a brass dome and safety valve. His bufferbeam is painted red, and his number is written on the sides of his cab in yellow writing.