What started as a relatively simple 'change of use' fire report quickly turned into a complex problem to solve the multiple historic issues with the building, including remediation of the extensive passive fire shortcomings. This project was our most complex and difficult computer modelling exercise to date, including sensitivity studies for the effects of wind and simulating the inclusion of a new stairwell pressurisation fan. However this effort ensured that our client received his Consent and the building is now considerably safer for all its occupants.