Joella Productions is a television production company based in London who have made Underground Ernie for the BBC. It was founded by John Deery and Sid Rainey, and named after Deery's son, Joe, and Rainey's daughter, Ella.
Logo
The logo is simply the letters J-O-E-L-L-A in spaghetti.
References
Joella Productions Wikipedia(Text) CC BY-SA