The "shop" featured in Bagpuss was in reality the rear of Peter Firmin's house. He decided it looked appropriate for the series and cast his daughter Emily as the girl in the monochrome introduction.
Peter Firmin intended Bagpuss to be a striped marmalade (orange) cat but the company who wove the striped furry cloth had a manufacturing fault and used pink thread instead of orange. This is the origin of Bagpuss the pink striped cat.
The first 2 minutes 51 seconds of each program is identical. This is an unusually long time, but did set the scene for new viewers. And of course children love repetition.
Apparently the stuffed toy that was to be used for Bagpuss was ordered from a supplier in Kent and meant to be a 'marmalade' cat. However, something went wrong with the dyeing process and it came out as a shade of pink. Peter Firmin and Oliver Postgate went with it anyway and the rest, as they say, is history...