The assault, which was filmed and has been described as “sickening” by Avon and Somerset Police, is thought to be linked to a recent “school wars” trend on social media.

Five teenagers who were arrested in connection with the incident, which happened on Wednesday 4 March, have been released on bail.

The girl’s dad, who we are calling Phil to protect the identity of the family, told the BBC she feels “let down” that witnesses did not intervene.