 During the Common Market referendum of 1975, Brotherton strongly attacked Edward du Cann who made a last minute anti-Market speech; Brotherton declared that du Cann "requires either psychiatric treatment or lessons in simple arithmetic".Brotherton demanded that the Royal Navy escort the British fishing fleet to defend it from Icelandic attacks during the Cod War.Early in January 1976 he challenged James Callaghan, then Foreign Secretary, to substantiate Sheila Cassidy's claim that she had been tortured in Chile before making any protest to the Chilean government.