There still seems to be some confusion about when this feast is celebrated: October 25 or May 4. The root of the confusion is that originally, when Pope Paul VI canonized the Forty Martyrs of England and Wales, the feast was on October 25, the date of their canonization--but it has never been celebrated on the universal Roman Calendar for all Catholics. Then in 2010, the Vatican approved changes to the Liturgical Calendar for the U.K., as this article from The Catholic Herald archives notes:
The feast of the English Martyrs is celebrated on May 4. The 40 martyrs canonised under Paul VI in 1973 (sic), previously celebrated on October 25, are celebrated with the 85 beatified Martyrs of the Reformation and the other martyrs of the 16th and 17th century. The feast coincides with the Church of England celebration of English saints and martyrs of the Reformation.
These are a significant group of saints in British Catholicism and include St Margaret Clitherow, the butcher’s wife from York who became a Catholic at the age of 18 and was arrested for harbouring a priest. She was crushed to death under a large door loaded with weights. St John Haughton (sic), St Robert Lawrence, St Augustine Webster, and St Richard Reynolds (sic) were Carthusian monks executed at Tyburn on May 4 1535.
St Cuthbert Mayne, another martyr, was a young man from Devon who went to St John’s College, Oxford, in the late 1500s, where he met St Edmund Campion and eventually became a Catholic.
Choosing the date of May 4 was appropriate, since the first martyrs, which also included Blessed John Haile, were executed for refusing to swear to Henry VIII's supremacy over the the Church of England on that date in 1535.
(To explain the two (sic) notations above: St. Richard Reynolds was not a Carthusian monk, he was from the Briggitine House of Syon; St. John's name is usually spelled Houghton.)
The "other martyrs of the 16th and 17th centuries" includes those beatified by Pope Leo XIII in 1886 and 1895 and by Pope Pius XI in 1929 who have not been canonized and also those declared venerable by Pope Leo XIII in 1886:
- In 1886, Pope Leo XIII beatified 54 martyrs, including Thomas More and Bishop John Fisher and 11 others who were canonized in 1970 by Pope Paul VI;
- In 1886, Pope Leo also declared 29 English Catholic martyrs to be Venerable (several of these martyrs had died in chains, that is, is prison or because of their treatment in prison);
- In 1895, Pope Leo XIII beatified nine more martyrs;
- In 1929, Pope Pius XI beatified 136 additional martyrs, 29 of whom were later canonized.
Just to complete the sequence of dates:
- In 1935, Pope Pius XI canonized John Cardinal Fisher and Thomas
- In 1970, Pope Paul VI canonized the 40 Martyrs of England and Wales
- In 1987, Pope John Paul II beatified the 85 Martyrs of England and Wales (which did not include any of those declared Venerable in 1886)
These martyrs suffered for different reasons:
The Supremacy martyrs died because they would not swear Henry VIII's Oath of Supremacy and Oath of Succession, which both denied the spiritual, moral, and ecclesiastical authority of the Pope. The Recusant martyrs died during the reigns of Elizabeth I, James I and Charles I because they continued to practice their Catholic faith in England as missionary priests and/or laity in spite of the recusancy and penal laws against them. Finally, the Popish Plot martyrs were executed in the miscarriage of justice called the Popish Plot. Accused of conspiring in a non-existent plot, their Catholicism condemned them: the priests were sometimes found guilty of their priestly presence in England under Elizabethan statutes when no involvement in the Plot could be found.