- "Ada, Jane and Mabel are plain. They have no roofs. Sir Handel says they are trucks, but they have seats, so I say they're coaches."
- ―Peter Sam, Home at Last, The Little Old Engine
Ada was built in 1955, Jane was built in 1956, and Mabel was built 1957. They were originally designed for carrying quarry workers, but are now used for tourist traffic on sunny days. Peter Sam mentioned them in a conversation with Skarloey, when he returned to service.
When a documentary was made about the Skarloey Railway, Ada, Jane, and Mabel had the honour of carrying the television equipment and cameras. They were later used for the same purpose when a documentary was made about Skarloey and Rheneas' hundredth birthday.
Ada, Jane and Mabel are plain coaches without roofs. Due to their appearance, Sir Handel considers them as trucks, but Peter Sam insist they are coaches because they have seats. As Ada leads the way, these three always find fun and laughter in a day's work. The coaches are very fond of Peter Sam.
Ada, Jane, and Mabel are based on the Talyllyn Railway's carriages 11, 12 and 13, with added buffers. The carriages were originally owned by the Penrhyn Quarry Railway, and have since been rebuilt with roofs. Replicas of the Penrhyn Quarry Railway carriages have been built for the Old Kiln Light Railway.
Ada, Jane, and Mabel are painted light blue. Their Wooden Railway models depict them with their names written on their backs in cursive.
- The Little Old Engine - Home at Last (do not speak) and Little Old Twins (do not speak)
- Gallant Old Engine - Steam Roller (one cameos)
- Very Old Engines - Duck and Dukes (Mabel only; cameo)
- 1972 - The Railway Series: Surprise Packet (do not speak)
- 1987 - The Island of Sodor: Its People, History and Railways (mentioned)
- 1996 - Thomas the Tank Engine: The Complete Collection (does not speak)
- 2005 - Sodor: Reading Between the Lines (mentioned)
- A fourth open carriage can be seen in the Surprise Packet.
- Ada, Jane and Mabel's Wooden Railway toys were some of the few toys made mostly of plastic rather than wood.
- Wooden Railway (discontinued)
- "Sir Handel says they are trucks, but they have seats!" said Peter Sam. "So I say they are coaches. What do you think Skarloey?"
- The old engine smiled. "If they have seats, they are coaches!" he said firmly.
- Peter Sam and Skarloey, "Home at Last", "The Little Old Engine".