In the British children's TV series "Bagpuss", Professor Yaffle is a representation of which animal?

"Bagpuss" is a British children's television series, made by Peter Firmin and Oliver Postgate through their company Smallfilms. The series of 13 episodes was first broadcast from Tuesday 12 February to Tuesday 7 May 1974. The title character was "a saggy, old cloth cat, baggy, and a bit loose at the seams". Although only 13 episodes were made, it remains fondly remembered, and was frequently repeated in the UK until 1986.

The programme shifted from sepia to colour stop motion film, and various toys in the shop came to life: Gabriel the toad (who, unlike most Smallfilms characters, could move by a special device beneath his can without the use of stop motion animation) and a rag doll called Madeleine. The wooden woodpecker bookend became the drily academic Professor Yaffle (based on the philosopher Bertrand Russell, whom Postgate had once met), while the mice carved on the side of the "mouse organ" (a small mechanical pipe organ that played rolls of music) woke up and scurried around, singing in high-pitched voices.