The Post Office takes over
Coldbath Fields closed as a prison in 1877...but the Post Office did not take over immediately. When they did, it was not without some controversy.
By 1887 a heated debate had developed as to what should be done with the large and gloomy site. The area of Clerkenwell was by this time polluted and overcrowded. The local authorities and groups like the Metropolitan Garden Association argued for the 8 acre site to be set aside for public gardens to benefit the health of the local people.
However, by August 1887 the Post Office had already moved in and adapted part of the vacant prison (the former treadmill houses) for use as a parcel depot. According to at least one newspaper of the time, the renovation cost £14,000 and was technically not legal as the Post Office had acted without an Act of Parliament.
There was a parliamentary inquiry: the groups in favour of communal gardens were countered by the local church who supported the acquisition. The church officials argued that what the community really needed was not open spaces, but "fifteen hundred respectable Post Office Servants" to enter the parish as rate-payers. This would, they felt, generate increased funds to care for the poor.
On 30 August 1889 the Post Office Sites Act was passed by Parliament, which officially transferred the old prison to the Post Office. It quickly developed into the principal parcel office and one of the largest buildings in the London postal service. It was an ideal location close to the three great railway stations on the north side of London: Euston, St Pancras, and King's Cross.
However, postal workers objected to working at 'Coldbath Fields', a name long associated with the feared gaol, so the designation 'Mount Pleasant' was formally used from 1888.