Dr. Beeke, if I remember correctly, from his lecture in the Puritans Conference (Puritan Literature) says something along the lines that even though many Puritan preachers were barred from ordination in the Church of England, due to non-conformity, that "the people" desired to have Puritan preachers, as they were most popular at the time. So then, these churches would have the properly and officially ordained Pastors from the state Churches, but hire the Puritans on as "lecturers" in a non-shepherding capacity. And that it worked as kind of a duel positive, in that the official preachers of each church only had to worry about the Sunday morning sermon, while the Puritan lecturers did the Sunday night, and mid-week sermon/lectures; and the Puritan preachers did not have to worry about the other shepherding aspects outside giving those lectures, and could focus on writing books (due to being ineligible for normal pastoral duties due to their non-conformity.)
From the 12:00-15:00 minute mark.