A physics teacher accused of having sex with a teenage boy begged a fellow student trying to blackmail her into sex not to "ruin my career over a nasty rumour", a court heard.

The unnamed student threatened to expose Eleanor Wilson's alleged relationship unless she had sex with him, Bristol Crown Court was told.

He sent her a series of messages to her school email account in February 2016, and threatened to send an anonymous note to the school's head teacher.

The first email, which was sent from an anonymous Gmail account on the evening of February 16, said: "I know about you and (the boy) and do you want that coming out?"

A short time later, Wilson received a second email, titled re: sexual activity, which said: "Reply in 24 hours or it will slip out. We wouldn't want that, would you."

The defendant replied: "I think you have got the wrong person's contact details."