Redevelopment of The National Archives' brutalist icon in Kew to allow diverse audiences to engage with the collection and each other.

The National Archives is the official archive and publisher for the UK government and for England and Wales. Its 11 million documents range from the Domesday Book to the Cabinet's recent meeting notes. With 250 million digital downloads a year it is seeking to translate the dispersal of information into new productive communities by transforming its Kew campus into a cultural destination.

In 2015 we were appointed to develop a masterplan for the redevelopment of 7,300sqm of public space in a brutalist building designed by the Property Services Agency and opened by Queen Elizabeth II in 1977. In 2017 we won the tender to develop and deliver the masterplan as Architects of The National Archives.

The existing interiors lacked the physical intensity of the exterior and had lost the clarity and generosity of the original plans. We provided a new welcome, lobby, public canteen and improved public gallery and retail. By removing the suspended ceilings to reveal the original coffered concrete ceilings and adding felt-lined downstands to create a range of spatial intimacies the ground floor spaces became conducive to reading, recreation and refreshment; alone and together.

The introduction of glazed rooms into the deep plan allows different users to do very different activities in adjacent spaces at the same time. For example, the auditorium screened Suffragette (2015) whilst the original documents from the film were enjoyed and discussed in the room next door.

Soft linings - felt downstands, carpeted terraces, thick curtains, bespoke chairs - help soften the raw concrete shell to make comfortable spaces for a range of activities. Connections between new insertions and the existing 20th century office decor were lined in mirror to make the interfaces more ambiguous.

The future phases of the masterplan to be delivered at The National Archives include

• a new Learning Centre to accommodate the 50,000 pupils visiting every year to handle original documents and explore multiple histories

New galleries

• The Safe Room, a new permanent gallery allowing visitors to discover the collection through originals, facsimiles and props
• A 400sqm temporary gallery for thematic, topical and touring exhibitions

• the Hall of Archives, a top-lit hall at the heart of the building providing all visitors a glimpse into the nation's repositories.