Catweazle's pet toad/familiar was called Touchwood.
The jaunty theme was actually a library piece called "Busy Boy" by Ted Dicks.
Ringo Starr and Marc Bolan were huge fans of the series, which is how Geoffrey Bayldon came to appear in Starr's Born to Boogie (1972).
Geoffrey Bayldon had turned down the role of "Doctor Who" (1963-present) resulting in William Hartnell being cast. He later said he regretted his decision as the show became hugely popular with children. Not wanting to repeat the same mistake he was elated when he was offered the role of Catweazle.