Police did not retrieve electronic equipment used by the codes and ciphers expert from GCHQ in Cheltenham until five days after his death. Equipment used by Williams at MI6 HQ in London took four days, Westminster coroners court heard.

Detectives relied on „assurances“ from senior security intelligence services (SIS) staff that equipment had not been tampered with, Anthony O‘Toole, a lawyer for Williams‘s family, told the inquest.

No formal witness statements were taken by police from intelligence staff. Instead detectives made a note or typed record afterwards, which was not later shown to the witnesses.