Holy Trinity looks medieval in its construct. The design is a Gothic survival, with some Baroque elements.
Buttresses and turrets line the outer walls. Ornate stained glass fills every window and icons stand above the door. The pews are Jacobean. Their cushions, and the altar cloth, are both purple velvet. In short, it looks Catholic, even to modern eyes.
In context, any surviving Catholic traces were being destroyed in every other church in the land. But this wasn't meant to be 'Popish'. It was determinedly and dangerously representing Laudian Anglicanism.
As well as the rebellious inscription above the door of Holy Trinity, there is a second one at the rear. It flanks the battlements around three walls and reads: Sir Robert Shirley Baronet founder of this church anno domini 1653 on whose soul God hath mercy.
He wanted there to be no mistake about who had built the Chapel of Holy Trinity. Nor could the protest message be missed.
Inside the church, the ceiling was painted with English Baroque finesse. All of the elements are represented, as is the Trinity.
The Tetragrammaton is proudly displayed, which is a provocative inclusion. The Name was considered so holy that it could not be shown in Catholicism, nor uttered in Judaism. (As late as 2008, the Vatican issued a directive that Yahweh could not be spoken in liturgy. This controversy isn't confined to the 17th century.)
But Sir Robert Shirley was an avowed Laudian Anglican and there was history with the Tetragrammaton. Archbishop Laud was put on trial in 1642, charged with including Catholic iconography in his own church.
In his defence, he pointed out that a woodcut, from the title page of the Book of Martyrs, featured a Tetragrammaton. It had just been published in a new edition and no-one had blinked about that. He had included nothing worse.
This argument did not save him. He was beheaded on Tower Hill in 1645. But it had been a famous statement, and now Robert had placed the same symbol in his church. That wasn't all. The ceiling art also featured Cromwell as a black dog, poised to pounce upon the Holy Trinity itself.
Around the edges were depictions of the ocean, in waves or sea-shells, which were probably an oblique reference to the exiled King Charles II.
The whole building was enough to have Sir Robert Shirley instantly arrested. That he wasn't showed that the Parliamentarians needed him to be free. Their intelligence agents were watching him very closely indeed.