The Office of Vigilance
The Office of Vigilance was founded by Archbishop Margery Ashcombe shortly after she assumed the position of Archbishop of Dises. She established it in response to the so-called curse that had plagued the office before her appointment - she was the sixth Archbishop appointed in only fourteen years, and the previous occupants had not fared well in the post.
Ashcombe held the firm conviction that the territory of Arvoringia, over which the Archdiocese of Dises presided, was a nest of hidden cultists and Old Church sectarians - equally heretical in her eyes - who would stop at nothing to undermine the mission of the Church of Albion. At its founding, she charged the Office to seek out, arrest, and bring to trial all those not loyal to the true Church of God in Heaven, and the agents of the Office of Vigilance have carried out her instructions with fanatical zeal.
The Vigilant
The agents of the Office of Vigilance are carefully selected for their unyielding commitment to the cause - no easy task, as it turns out. Few among the clergy of the Church of Albion share Archbishop Ashcombe's views deeply enough to accept her methods, and her fellow archbishops have sought to censure her in the General Conclave - only to be blocked by Empress Charlotte, in her authority as Supreme Head of the Church of Albion.
Still, while the clergy of Albion are reluctant, there remain many among the laity - failed priests, war widows, and former soldiers - who are eager to take up the cause. As word of the Office of Vigilance spread, these warriors for God in Heaven presented themselves before the Archbishop, who examined them personally and gave free rein to all she found acceptable. They are known collectively as the Vigilant, and have spent the past two years bringing the Doom of God in Heaven to the people of Arvoringia.
Means and Methods
One of the most controversial aspects of the Office of Vigilance lies in the methods employed to obtain confessions from those they suspect. While most of the Church of Albion now regards torture as a relic of the past - and of the Old Church - Archbishop Ashcombe and the Vigilant consider it a grave mistake to have set such tools aside.
When examining the suspected for collusion with unholy forces, they claim to break through whatever eldritch protections the cultists may possess by wielding the Malleus Agoniae, the Hammer of Agony. They point to specific verses in the Book of Prophets which, according to their interpretation, sanction this practice, and they have become masters of it in surprisingly short order.
Through the application of this hammer, they have extracted countless confessions from those who claim to have worshiped entities from Beyond - most often Leviathan - thus confirming their conviction that Arvoringia is rife with the enemies of God in Heaven.
These confessions are then presented before the Archbishop's court for the pronouncement of Doom. This is most often a sentence of death by burning, for the judges place little faith in the repentance of liars and cultists. A few of the most penitent - and the most helpful to the Vigilant in identifying others of their ilk - are granted decades of hard labor as penance, though such mercy must be purchased dearly with the names of many of their co-conspirators, sometimes encompassing whole villages.
A Thousand Torches
Since the founding of the Office of Vigilance, nearly a thousand souls have been executed in mass burnings held outside the city of Dises. During the first of these executions, crowds attempted to disrupt the proceedings, but after several such incidents, the Archbishop requested - and received - a company of Taloi from the Army of Albion to guard the pyres. Her instructions were clear: any who attempt to rescue the condemned are to be cast upon the flames with them.
"The Doom of God in Heaven is unavoidable," she has said, "and we shall not tolerate those who would delay it."

So people critical of the diesis are hunted by a 'secret' police?
Oh, they aren't secret. They are hunted very publicly.