This was built in 1852-3 as a chapel of ease to the parish church of St. Mary to serve the area to the east of the town. The church was designed by C.H. Gabriel and is tall, of coursed rubble and in the Decorated style. It has a west bell cote and spirelet. The churchyard replaced that of St. Mary's, which was overfull, as the parish graveyard. An assistant curate was appointed to serve Holy Trinity by the vicar of Calne. The church was not licensed for marriages until 1990.