No More Teachers Bromwell High : Season 1 Episode 4

After a smashing performance at the school music evening, Mr. Anderson, the English teacher, is offered a career as a pop star, leaving the rest of the teachers to think about thier own pathetic and unrewarding careers in the classroom. Depressed and dreaming of a better future, they all resign (except Mr. Phillips, the P.E. teacher) and Iqbal is faced with the problem of replacing an entire staff. ... with rhesus monkeys!