Sooty's had lots of breaks, changes of formats and the companies producing it as well, Blue Peter hasn't.
What time did it change from a studio show in front of an audience to them living in a house? I presume around the time Matthew took over.
As Neil says above, it was from January 1981 - actually Matthew’s fifth series. That was when the familiar 80s opening theme was introduced.
Series 4, from early 1980, was the one where each episode ended with “Sooty’s Disco”. The Christmas Pantomime, first shown in December 1980 but repeated until
at least 1982, was the last audience-based show.
Cut out the coupon in your TV Times!