By 1754, the Anglican population of Lancaster was too large to be solely served by St. Mary's Church (Lancaster Priory) so a subsidiary chapel-of-ease, dedicated to John the Baptist, was built here at Green Ayre, then the industrial heart of the port town. As the photo shows, the nave and aisles were supplemented by wide galleries on three sides, so it must have had a considerable capacity.
The floor of the nave is occupied by numbered box pews, most of which were leased to local worthies.
Thomas Harrison's tower was added in 1784, a small porch in the 1870s and two chapels in the 1920s, but the body of the church has remained fundamentally unchanged for over 250 years.

I don't know when, or even if, St. John's became a parish church in its own right, but declining congregations led to its closure in 1981. I'm glad to say the building seems well-maintained by the Churches Conservation Trust and is regularly opened to the public, not only for Heritage Days like today but for concerts. Nothing suggests it's been deconsecrated, so I suspect services are still held on key holidays.