Bain, who has spent 15 years in brewing industry PR and previously headed comms for Carlsberg-Tetley, is leaving to join Hilton Group in the newly created role of vice-president of media relations.
She will report to Hilton Group director of corporate affairs Alex Pagett.
Her exit follows the May appointment of HR director Eleanor Cannon to the executive board and the post of director of corporate affairs (PRWeek, 20 May). S&N is now on the hunt for a replacement for Bain.
S&N, which is behind brands such as John Smith's bitter and Strongbow cider, was the subject of takeover speculation last month after reports that SABMiller would bid for the company.