She is scathing about residents' groups which are "transmission belts" for the IRA, undemocratically formed and cowering internal Catholic dissent with vociferous machine politics that smell of fascism.
Their leaders are often republican convicts who seek to divide Protestants and turn them against the British State. These groups began as a part of Gerry Adams' strategy of "angry voices and marching feet." Mo Mowlam is reported to have told Orangemen of the IRA strategy to destablise Northern Ireland and warned them not to walk into the trap.
But Catholics on the Garvaghy Road and elsewhere have reasons to fear the worse. Many have been beaten and murdered. Residents' groups have prospered and acquired legitimacy because they were able to tap into and organise deep fears of Catholics being what some call the "white niggers" of the north.
It is also as important to distinguish between Orange marchers and loyalist terrorists as it is to distinguish between residents and those republicans who create or exploit these confrontations. But Orange parades are tarnished by the presence of "Kick the Pope" bands.
She takes us, with an acute mixture of vox pop, analysis and personal observation, through the bloody, frightful and more peaceful stages of Drumcree 1 through to 5. This year's Drumcree was relatively peaceful but in 1996 Northern Ireland seemed to be on the verge of civil war.
It ends with a draft speech for the Prime Minister advocating stability and conciliation, written by her and others including former IRA commander Sean O'Callaghan.
This is not a comprehensive history of the Order. But her highly readable account brilliantly burrows into the heart of the Orange and Protestant psyche - from the triumphalist to the decent, teetotal (sometimes), stubborn, indecisive, inarticulate and frequently stupid.
The Orange is said to have proved to be the "Provisional's greatest ally." She may be sympathetic to their plight but is not duped by them. She quotes an Orange friend saying that "Billy Wright has filled the vacuum that is Harold's head." Harold Gracey  is the Portadown Orange leader who has lived in a caravan at Drumcree ever since the parade was banned in 1998.
She also occasionally makes irritating and injudicious generalisations that spoil her case. For example, she writes that whilst Protestant men bond in the Order, Catholic men bond in the pub or the Gaelic Athletics Association. Most do none.
She also says that the qualities that enable the Protestant community to endure siege conditions don't allow for intellectual nimble-footedness and public relations talent. Up to a point, Lord Copper. These are sometimes precisely the conditions which nurture such talents. There is a desperate need to deepen the pool of political talent on both sides of the sectarian divide.