Because of delicate health, Henry was, at first, educated privately at home, and then later at Christ Church, Oxford (1883–1886), where he received a first-class degree in Classical Greats.

[2] Having trained at Cuddesdon near Oxford, Chapman was ordained as a deacon in the Church of England in 1889 and began a curacy in the parish of St Pancras, London.

After his priestly ordination in 1895, he went to Erdington Abbey, near Birmingham, where he stayed until 1912, serving the community as novice master and later as prior.

[5] Having spent nine months at Maredsous, in February 1913 Chapman was made temporary superior of the Caldey island community (now based at Prinknash Abbey), when it was received into the Roman Catholic Church in 1913–14.

[5] At the outbreak of World War I, Chapman became a Professor of Theology at Downside Abbey, joining the many monks who had fled Maredsous to England.

Among the novices that Chapman clothed in the monastic habit was in 1932 John Bernard Orchard, who soon felt drawn to follow his Abbot into researching the priority of the Gospel according to Matthew in the light of the patristic evidence, and eventually, after also constructing a synopsis of the four Gospel accounts in Greek and English for the easier study of the compositional sequence Matthew-Luke-Mark-John that is supported by certain early Christian writers, produced what by hindsight may be considered a synthesis of his and his mentor's insights.