Leon Brittan, the Home Secretary, commented: "The nature of a terrorist organisation is that those in it are not under disciplined control".[1] In his book The Provisional IRA in England, author Gary McGladdery says the bombing illustrated one of the problems with the IRA's cell system, where units "could become virtually autonomous from the rest of the organisation and operate at their own discretion".[12] The IRA had adopted the system in the late 1970s.[13]