teddytoot, even in Wilbert's books, Falcon and Stuart were blue and green, and both changed to red when they went to the Skarloey Railway. Plus, the railway that Bulldog takes place at is not the Skarloey Railway, it's the (now lifted) Midland Sodor Railway.
Correction: The Skarloey Railway is actually 2' 3" (27"), just like the Talyllyn Railway. hbl stated that the Skarloey Railway is a twin to the Talyllyn Railway. All the narrow gauge railways on Sodor are 27 inches, (except the Culdee Fell Mountain Railway which is 2' 7 1/2", and also does not include the Arlesdale Railway, as it's miniature gauge).