Ultimately, it was Lady Caroline who prevailed on her husband to agree to a formal separation in 1825. Both parties had had numerous extramarital affairs by that time and Lamb had long been known to eschew duplicity. She took up permanent residence at Brocket Hall. Her struggle with mental instability became more pronounced in her last years, complicated by her abuse of alcohol and laudanum. By 1827, she was under the care of a full-time physician as her body, which had always been frail, began to shut down and she retained fluids (a condition then known as dropsy, and now known as oedema). William Lamb was Chief Secretary for Ireland by that time and made a perilous crossing to be by her side when Lady Caroline died on 25 January 1828.