Definition & Meaning of "mumble-matins"in English

What is the origin of the term "mumble-matins" and how is it used?

"Mumble-matins" is a British slang term that emerged in the 18th or 19th century, combining "mumble," referencing quiet or indistinct speech, with "matins," the early-morning prayer service in the Catholic Church. It was used to mock Roman Catholic priests, implying that their prayers or religious observances were mumbling, secretive, or ineffectual. The term appears in informal speech, satire, and sectarian commentary. It is clearly derogatory, targeting both religious role and perceived ineffectiveness or eccentricity.