We carried out a historical replacement of Second World War reinforcement to the wall of the Treasury. Works were undertaken under the stewardship of English Heritage with particular requirements to ensure only traditional methods were utilized while ensuring modern and sustainable products were used. Due to the location, there were a series of operational requirements that made this project particularly difficult from a logistical aspect. Security was an issue and work had to be carefully planned to coincide with visiting dignitaries, changing of the guard and trooping the colour parade.