Sumsion asked Howells if he had anything that could be performed at the 1950 Three Choirs Festival to be held at Gloucester. Howells decided to bring out the incomplete choral work he had written in his son Michael's memory between 1936 and 1938. (In later years Howells claimed it was at the urging of Vaughan Williams that the piece was disinterred). The work, retitled Hymnus Paradisi at Sumsion's suggestion, was completed and orchestrated in time for its first performance on 7 September 1950, the day after the 15th anniversary of Michael's death. It was Howells' greatest public and critical success, and for many years was his best known work. Shorter choral works written around this time include the carol-anthem Long long ago (1951), the introit Behold O God our Defender for the coronation of Queen Elizabeth II in 1953, and The House of the Mind (1954) for chorus and strings. Though not an orthodox Christian, Howells was now chiefly identified with the composition of religious music. His follow-up work to the Hymnus Paradisi was an extended setting of the Latin Mass for soloists, chorus and orchestra, named Missa Sabrinensis after the River Severn and first performed in Worcester Cathedral as part of the Three Choirs Festival in 1954. It was considered a disappointment after the success of the earlier work, and its extreme complexity and difficulty has prevented it becoming widely known. The critic Michael Kennedy, however, considers it one of Howells' finest works. Howells followed it with An English Mass (1956), a smaller-scale setting to English words for chorus, strings and organ. His final large-scale choral work was the Stabat Mater, setting a text whose subsidiary theme of a parent mourning a child had obvious personal significance. He began it in 1959 but found it difficult to complete; it was not performed until 1965. The motet Take Him, Earth, For Cherishing, a posthumous tribute to President John F. Kennedy, was written in late spring of 1964. It premiered as part of a 22 November 1964 Canadian tribute to Kennedy at Washington's National Gallery of Art sung by the Choir of St. George's Cathedral, Kingston, Ontario, Canada, under the direction of George N. Maybee. Maybee brought the St. George's choir to England in September 1965, and they performed the piece at King's College, Cambridge with Howells in attendance. Take Him, Earth is described by Howells' pupil Paul Spicer as "a