The 9,000 sq ft property is part of the development built by main contractor Laing O’Rourke for a consortium including the Candy Brothers.
O’Rourke finished the main contract in 2009 and public information about flat owners and sale prices has been scarce ever since.
The £65m flat is up for sale via agents Aylesford International.
It is described as “an exceptional apartment stretching across the entire floor plate of pavilion C and as such boasts magnificent views of both Knightsbridge and Hyde Park.”
The apartment has five bedrooms and is split into two wings built around a 65 metre hallway.