The MSP building is linear in plan, stepping down from five storeys to three towards the south of the site. It contains a series of individual cellular offices on the west side and an open plan office/corridor area on the east side.
The structure is a combination of in situ and precast concrete, a choice determined by the requirements for the structure to resist bomb-blast and withstand terrorist attack. The cellular offices on the west side are constructed from precast-concrete vaulted ceiling units which span between in situ concrete portal frames; each office has a projecting prefabricated bay window unit.
The east elevation faces an internal garden and is mostly glazed. The corridor on each floor is formed by a cantilevered concrete slab supported by beams which extend from the portal frame. To take light and air into the centre of the plan, a stainless steel-clad unit with a motorised glazed vent to the rear was prefabricated and bolted to the underside of each corridor slab. The units generally span the full width of the corridor.
The glazing - oak windows clad with stainless steel - is supported by a robust steel structure which transfers blast loads. A series of precast concrete louvres, laminated oak louvres and solid stone panels supports 250 x 120mm precast concrete mullions bolted to the steelwork. The louvres, panels and mullions are arranged to form a series of repeating patterns which are handed from floor to floor. On the outside of the louvres, a stainless steel gutter system takes water from the roof and the recessed vents and directs it down the external facade by means of troughs, chutes and diagonal gutters.