This information is taken from the Church's free information leaflet

The Church was built in 1776, the year of the American Declaration of Independence. Its plain classical style resembles many of the New England churches. It replaced the old and dilapidated Church in Rectory Grove, now rebuilt as St Paul's. Designed by an Office of Works architect, Kenton Couse, as a plain "preaching box", dominated by an immense three-decker pulpit at the east end, Holy Trinity has been changed very much over the years. The late 19th century wanted the altar to be the focus of worship and moved the pulpit. The Chancel and a Lady Chapel were added in the early 20th century. Today further changes have turned that Lady Chapel into a community centre, put a screen across the west end, giving space for a new, much smaller chapel, and a meeting place.

The time of the greatest nation-wide glory of this parish was the late eighteenth century and early nineteenth century when it was the home of a remarkable group of public men who dedicated their lives, their fortunes and high talents to the fight against the slave trade and many other causes, at home and abroad. The best known of these was William Wilberforce, whose name has been given to the Community Centre. The Thornton family, bankers and merchants, were perhaps the most deeply rooted in Clapham, and the new Chapel is called after them. The parish school has the name of another of the group, Zachary Macaulay, and also of his son, TB (Lord) Macaulay, the historian. The names of all the members of this "Clapham Sect" are on a tablet outside the Church.