When the next general election comes, UK schools are unlikely to be packed with staff wearing badges saying “Classroom assistants for Cameron” or “KS3 teachers 4 Gordon”. But, as always, they do things differently in the United States.

Teachers at a high school in California have agreed not to wear “Educators for Obama” badges in lessons after a parent’s complaint.

John Hadley, a Republican-voting parent, said: “It doesn’t matter who they are supporting. Teachers lose their free-speech rights when they go into a classroom.”

Handily, California has state laws that set out when and where teachers can don political paraphernalia. Wearing an Obama T-shirt or badge to school is fine, but staff must remove them during lessons.

Mr Hadley heard about the badge-wearing teachers from his 16-year-old daughter, Teegan.

She said it would have been just as wrong if teachers had worn badges supporting John McCain, but added: “I probably wouldn’t have told my dad about it.”