Egle was first poisoned with antimony, and he had several days off work with diarrhoea and severe stomach pains. His health improved after a week-long holiday, but on his return Young put a lethal dose of thallium in his afternoon tea. Egle's condition deteriorated rapidly from this point. He complained of intense back pain and numbness in his fingers and feet. He was transferred to the intensive care unit at St Albans City Hospital, where paralysis set in. Young showed a strong concern for Egle, repeatedly contacting the hospital for updates on his progress. Egle finally died on 7 July 1971. An autopsy attributed Egle's death to a rare form of polyneuritis known as Guillain–Barré syndrome. Young was chosen to accompany managing director Godfrey Foster to Egle's funeral, as a representative of the department Egle managed. Foster recalled Young remarking how sad it was that "Bob should come through the terrors of Dunkirk only to fall victim to some strange virus."