More from: Boris calls in Mount Pleasant overhaul
The architect has been given the green light to design proposals for a 55,000 2mixed-use scheme.
A source from Royal Mail has confirmed that poor working conditions and the need for new technology have prompted the major rethink of the site, parts of which could be sold off to finance an upgrade of its buildings there.
Records relating to the site date back to the Middle Ages. According to Royal Mail, the name Mount Pleasant was an ironic slant on the site's original use - as a rubbish pit.
In the 19th century it was the location of a 'house of correction' before being acquired by Royal Mail in the 1880s, when a parcel-sorting building was constructed there.
This was followed in 1926 by the construction of a letter-sorting building, still present today. The parcel building was demolished in the 1980s.
McAslan to transform Mount Pleasant