The government’s support for schools attacked for promoting LGBT+ inclusion has been “half-hearted” and has left many teachers “exposed”, public figures and religious activists say.

Author Philip Pullman and Tory MP Crispin Blunt are among 77 signatories of a letter to the education secretary following months of protests outside schools against LGBT+ lessons.

The open letter says government guidance, which says primary schools are encouraged to cover LGBT+ content if they consider it “age appropriate”, has been “weakly ambiguous”.