Bluebell and Primrose are tank engine twins who live on the Bluebell Railway.
- Despite not having faces, Bluebell and Primrose were the first female steam engines to be introduced in the Railway Series.
- Of the two engines, only Bluebell is currently operational. Primrose is undergoing restoration.
- Although in the illustrations Bluebell is shown in SE&CR pre-World War I livery she was actually painted blue from 1966 to 1998.
- Bluebell's ERTL model was in fact Thomas' model merely repainted and with a different smokebox. She was originally going to have her own model. This original (prototype) model had a crew member leaning out of her door. This would have been the only ERTL model to have this feature.
- Ertl (Bluebell only)