Great Britain disciplinary meeting: can I take someone with me?

Under the Acas disciplinary and grievance framework, workers have a statutory right to be accompanied at a formal disciplinary meeting that could lead to a warning or other disciplinary action, and at formal grievance meetings, if they make a reasonable request. The companion can usually be a fellow worker or trade union representative or official. Official source: Acas. Guide: https://getinstantlaw.com/employment-workplace-problems