PCA was commissioned to undertake historic building recording in connection with the replacement of the protective timber staircase in the Flamsteed Turret at the Tower of London. This turret is one of the four turrets at the corners of the White Tower at the centre of the Tower of London. The Tower of London is a UNESCO World Heritage Site and a Scheduled Monument. Designations of this level recognise that the Tower of London and its buildings are of international significance. The Tower also lies in the Tower of London Conservation Area. The White Tower is designated as a Grade I listed building. PCA was able to provide suitable specialist staff to ensure that the work undertaken at this important site was done to the highest standards.
Removal of the protective timber staircase uncovered the original early medieval spiral stone staircase. The White Tower is known from previous building analysis to have been constructed in two phases: Phase 1 from c.1075 to 1080 and Phase 2 from 1090 to 1100. The break in construction from 1080 to 1090 was also identified in the steps. The Phase 1 stone pavers steps were constructed of mainly of malmstone as well as Caen stone, Reigate stone, and Quarr stone. The Phase 2 stone pavers steps were constructed of mainly of Reigate stone with the continued use of Quarr stone and occasional Bembridge Limestone. It was found that medieval mortar was used as a levelling layer beneath, on top of and along the vertical faces of each stone step. Remains of black carbonised wood impressions on the surface of the mortar show that the steps had been covered with timber boards that had since been removed.
The protective timber staircase was made of oak boards that may have been put in place in the early 1970s. Graffiti on one of the timber treads was ‘1971’ and on another was 04/04/1991). Datable finds under the covers included a 1960 shilling, 1995 and 2001 tickets and a 2007 tourist leaflet.