In 1821 six treadmills were installed to power a corn mill in the prison. He built a large prison arranged in a half octagonal plan with an octagonal governorвЂ™s house at the centre to oversee the exercise yards contained within the main wings. In 1819 the Surrey magistrates commissioned Thomas Chawner to build a new House of Correction. A substantial part of the original design has survived despite later alterations and additions. Each prison block was separate from every other one, linked by iron walkways, with wings divided longitudinally to double the number of categories of inmate that could be accommodated separately. The early prison consisted of a large, central tower accommodating the two governor offices and a chapel on the top floor, from which three cruciform complexes of blocks radiated. The first stone of the new prison designed by the architect Daniel Asher Alexander was laid in 1810 and in 1819 the first inmates begin to arrive, though work continued until 1822. Despite major alterations and additions during the following 180 years, parts of BlackburnвЂ™s original prison and the crescent have survived. In 1834 a crescent shaped wing was erected, the only example of this plan type in an English prison. Begun in 1787, the original building consisted of a quadrangle with projecting wings similar in design to his prison at Gloucester. HMP Stafford was the brainchild of the pioneering prison architect William Blackburn. Historic EnglandвЂ™s prison expert Allan Brodie chooses 10 of EnglandвЂ™s most interesting urban prisons* that help to tell the story of 250 years of imprisonment.

Prison architect cell grading