John Myles, in 1662, was ejected from the living of Ilston, in Wales, by the Act of Uniformity. Like a considerable number of Baptists in the time of Cromwell’s protectorate he was probably pastor of a Baptist church, and officiated as a preacher in one of the state churches. The law, in 1662, compelled him to surrender his relations to the Establishment, and subjected him otherwise to great sufferings if he would carry out his conscientious convictions. He had been a very active and successful Baptist minister. Backus represents him as the “father of the Baptist churches in Wales, which began in 1649.” This statement requires some modification, but it is certain that he was exceedingly useful in spreading the truth in the principality. And had he not been a man of strict conscientiousness he would have retained his living in the national church and sacrificed his religious principles. Many followed this course.
In 1663 he and his Baptist friends of Swansea, in Wales, came to Massachusetts, and located at a place to which they gave the name of their old home. They brought their church records with them, and they joined together “in a solemn covenant” (in a church organization) in the house of John Butterworth. John Myles was the pastor of the American Swansea church. He was a minister of great industry and zeal, and of fearless courage. When the Boston brethren suffered heavily from the persecuting laws of their Puritan brethren, Myles went to succor them, and give such counsel and encouragement as his wide experience would readily furnish. He stood his ground in Swansea against all discouragements and threatenings, and proved himself a tower of strength to the abused and persecuted Baptists. He remained the pastor of Swansea till his death, in 1683.
John Myles was distinguished for his learning, and remarkable for his piety, and such was the blessed influence which he exerted, and the deep impression which he left, that Backus writes of him in 1777, nearly a hundred years after his death, “his memory is still precious among us.”
William Cathcart, The Baptist Encyclopedia