The National Gallery is a Grade I listed Wilkins Building located in Trafalgar Square, London. This £15 million project required to us to refurbish the Basement and Ground floors of this live building as well as infilling two lightwells which would create additional workspace. The additional spaces included offices, meeting rooms, breakout rooms and toilets. During this time, not only were we faced with working alongside an occupied building with associated demolition and noise but also the discovery of unforeseen construction, often found with buildings of this kind. Our previous experiences working within a Grade I listed building assisted our understanding of potential limitations and cost impacts of the works resulting in another successful project.