A mother-of-two was strangled to death by her partner who had an obsession over their relationship, Cambridge Crown Court heard today. John Mearns, who has been in custody at Peterborough and Norwich since February, is on trial charged with the murder of 54-year-old Pauline Smith on October 26 last year. The jury of 12 men and women listened as Allan Mainds, prosecuting, told the court how Mearns became violent when he feared the relationship was over He said the 53-year-old applied a strong and sustained pressure for what must have been minutes to Ms Smiths neck, fracturing her voice box and cutting off her air supply. The court heard that Mrs Smith left the family home in Somersham in spring last year after meeting Mearns at a dance and beginning an affair. She moved into a one-bedroom flat in Gainsborough Drive, St Ives and lived on her own. Mearns, of no fixed address, denies murder but has pleaded guilty to manslaughter. He is expected to argue that he did not intentionally harm Ms Smith nor intend to kill her. The trial is expected to last for three week.