The present church was opened on 26th July 1871. It was built to cope with the changing needs of Llandrindod, which is a Victorian settlement. At the beginning of the 19th century the combined population of the parishes of Cefnllys and Llandrindod amounted to no more than 500. However the extension of the railway line from Knighton led to the development of extensive building.
The church took 2 years to build at a cost of £2457. It was at first dedicated as Christ Church but when it was consecrated on 7 September 1882 it became Holy Trinity, using the dedication of the Old Parish Church which gave the town its name.
The original building contained seating for 500 people, but the church was extended a number of times. These extensions included a baptistry, a vestry for the choir, a new north aisle, extensions to the chancel, construction of the Lady Chapel, as well as the vestries and organ chamber. The seating capacity had been increased from 500 in 1871 to 1400 in 1910. In 1995 a tower was built to accommodate a peal of bells. As part of the modernisation of the church, the north aisle was converted into a church centre, the Saint Francis Centre (named after the modern stained glass window above the kitchen,) with catering facilities. At this time the former baptistry (at the west end) was converted to a Memorial Chapel.
One of the banners decorating Holy Trinity
"The fruit of the Spirit is Love, Joy, Peace, Patience, Kindness, Goodness, Faithfulness, Humility and Self Control"
INCUMBENTS OF THE PARISH OF CEFNLLYS AND LLANDRINDOD
1871-1881 The Rev'd Thomas Thoresby
1881-1895 The Venerable Archdeacon Henry de Winton
1895-1929 The Rev'd Canon R W F Singers-Davies
1929-1946 The Rev'd Canon Griffith Thomas
1946-1954 The Rev'd Canon J J Hughes
1954-1975 The Rev'd Canon W J Davies
1976-1998 The Rev'd Canon G M Hughes
1998-2009 The Rev'd Canon A Loat
2010-2013 The Rev'd I Rees
INCUMBENTS OF THE PARISH OF GLAN ITHON
2015-2016 The Rev'd Canon J Penberthy
2017 The Rev'd Andrew Perrin