Tokyo-based real estate company Mitsui Fudosan confirmed on Wednesday (19 March) that it will fund the 1.1 billion project.Work to deliver the development will be able to proceed as soon as possible, according to the company. Detailed design will start now and initial works are scheduled to begin in 2026 for an estimated completion in 2032.The massive extension to Colin St John Wilson and MJ Longs 1997 landmark, which RSHP designed alongside Arup as engineers, was approved by Camden council in July 2024, despite concerns over its height and bulk.AdvertisementRSHP had won the the high-profile job seven years before, when it and Stanhope were selected following a developer-led competition back in 2017.The extension will see two blocks built north of the main British Library building, creating a new home for the Alan Turing Institute and nearly 10,000m2 of library facilities, as well as additional life sciences and office space. Long & Kentishs 16-year-old conservation centre will be demolished to make way for a 12-storey building next to the Francis Crick Institute.The extension will provide 9,290m extra library spaces for culture, learning, research and business uses, including doubling existing gallery space, to enable hundreds of thousands more visitors to be admitted each year.It will also include around 55,800m of commercial life sciences space, for occupants seeking to locate close to the Francis Crick Institute, Alan Turing Institute and the rich mix of other organisations located in Londons Knowledge Quarter.The extension will be linked to the existing library building via new circulation areas, including a new full-height foyer and new public entrances.AdvertisementIt will open up the library across three sides and include new, publicly accessible internal and external routes connecting the building to Somers Town and St Pancras. DSDHA has worked on the landscaping and public realm for the project.Under the terms of the agreement, the British Library will grant a long lease of the land to SMBL, its development partner, which will now become fully owned by Mitsui Fudosan as part of a restructuring of the investment partnership. Stanhope will be kept on as development manager for the project.Takeshi Iwama, chief executive of Mitsui Fudosan UK, said: Our development commitment represents what we believe to be one of the largest single real estate investments into London by a Japanese company to date.We have already acquired significant expertise in the life sciences sector across Japan and the US over almost a decade and will be bringing this to the British Library extension development, our first in this sector in Europe.Iwama added that the company was confident that the new life sciences space in Kings Cross will encourage some of the worlds most ambitious and successful life sciences companies to invest in the UK by the early 2030s.Culture, science and technology minister Chris Bryant said: The British Library is one of the greatest British cultural institutions and this funding will see it undergo an ambitious transformation, creating new spaces that will showcase our national story and history.The creation of a new world-class commercial science and innovation space in Londons Knowledge Quarter will also help encourage investment in this vital sector in the UK. I look forward to seeing how this major development will benefit the local community and beyond, supporting growth and innovation.Rebecca Lawrence, chief executive of the British Library, said: Our partnership with Mitsui Fudosan will enable us to fulfil our long-held vision to extend the Librarys site in St Pancras.The plans will open up the library even further, creating an expanded national library with state-of-the-art new spaces, harnessing the power of collaboration to build a new public realm linking communities and the Knowledge Quarter and deliver significant investment in the UK.The British Library has confirmed it will be seeking the support of visionary philanthropists and partners to fund the internal fit-out of new spaces.The development agreement includes a 23 million contribution towards affordable housing in the area, commitment to affordable workspaces, including incubator desks within the Librarys new business spaces, and a new community garden on Ossulston Street.RSHPs initial proposals sparked anger from conservation groups over the planned demolition of the existing 13 million conservation centre building, designed by British Library co-architect Long & Kentish and only completed in 2007.Revised plans unveiled in 2021proposed pulling back the new building from the western edge of the site to reduce the impact on the residents of Somers Town, Ossulston Street and Levita House, as well as Midland Road.Historic England said during the consultation phase that RSHPs scheme would still cause some harm to the surrounding heritage assets but that it supported the designs and relocation of the conservation centres collection into the heart of the main British Library building.The scheme aims to complete original architects Colin St John Wilson and MJ Longs intention for the wider library site and the 1.2ha plot to the north of the existing 1997 library, using private developers rather than public funds.