Jane Pit was a 19th century coal mine built by Henry Curwen who was lord of the manor in Workington. Jane Pit is the best surviving example of the ornate castellated style of colliery architecture that was a feature of the Cumbrian coal industry at the insistance of the powerful landowners involved during the nineteenth century.
The remains on the site are the pumping engine house (1844) and the chimney for the winder boilers (1843), constructed while the shaft was being sunk (commenced 1843, much troubled by gas and water). The supposed "gin circle" is speculation on behalf of Allerdale's scribe, no need when a steam winder was there from the start - and the pump house stands between the "circle" and the shaft. The feature is more likely to have been a small reservoir for the boiler feed.
The pit was never very productive, producing little after 1862/3 and was used later only in connection with Annie Pit (1864) for pumping and ventilation until 1875. It closed because the lessee went bust and turned the pumps off - no inrush of the sea (it's completely under land), no 100 entombed miners (that seems to be a confusion with and exaggeration of the 1837 inrush at Lady, Isabella and Union Pits, which was the sea and in which 27 died).