By the 13th century the castle had become the county gaol.

Thornton was held in the county gaol pending the trial.

The present office was first established in the town in 1967, within the former county gaol.

In the last two decades of the century, around £30,000 was spent rebuilding Lancaster's county gaol.

The justices had responsibility for maintaining county gaols and houses of correction.

The County Gaol was located a short distance from the court rooms.

For a time it served as the county gaol and later a windmill stood on the castle mound.

In the 18th century it became more common for county gaols to hold longer term prisoners; as a result they began to suffer from overcrowding.

The Castle mound (motte) is the largest in the country, and from the 14th to 19th century the keep was used as a county gaol.

It is apparently still the case that in some local, county gaols adults and juveniles are housed together, sometimes for periods of several weeks.