The simple architecture of Rainham's modern Catholic church (built 1955-1957), on the main road from Rochester to Canterbury, is decorated only by a grandiose, colourful tympanum hung low over the main entrance, a typical work by Adam Kossowski from his most active period in religious art.

The plastically rich relief of the tympanum shows two independent scenes, separated in the uniform field of the tympanum by the coats of arms of Pope Pius XII (during whose pontificate the church was built), and joined compositionally in the setting of a fanciful sacred building, forming a frame for the whole. On the left, the church's patron saint, the Bishop of Canterbury St Thomas Becket, stands beside the throne of King Henry II, surrounded by an entourage; on the right, the martyrdom of St Thomas is depicted: a soldier plunges a sword into his breast; two monks turn away from the scene in horror. The bishop was a friend of the king, with whom he later came into conflict and on whose orders he was murdered in Canterbury Cathedral. Kossowski captured this relationship between the two figures in an abbreviated visual metaphor. The artist was commissioned as a result of his increasing notoriety among the English Catholic clergy, brought about by his work for the nearby Carmelite monastery at Aylesford. The tympanum was made in Kossowski's London atelier on Old Brompton Road, strictly in accordance with the dimensions and recommendations provided by the church's architect, Eduardo Dodds, in his design. The styling of the tympanum is modelled, more clearly than in Kossowski's other religious works, on Romanesque miniature painting, referring to the era of Bishop Becket (d. 1170). Inside the church there are other works by Kossowski, a depiction of St Joseph with the Child and reliefs with angels.