Mitsui Fudosan UK Limited Breaks Ground on £1.1 Billion British Library Extension in King's Cross

Mitsui Fudosan UK Limited marked the start of construction on the British Library extension in London's King's Cross Knowledge Quarter with a groundbreaking ceremony on 21 September 2026, the firm announced. The event followed the Japanese tradition known as 'Ji chin sai' and took place on site at 96 Euston Road, London NW1 2DB, beside St Pancras and King's Cross stations.

The development, valued at approximately £1.1 billion, is being delivered by Mitsui Fudosan UK with the British Library and Stanhope. Completion is targeted for 2032.

Groundbreaking Ceremony at the British Library Site

Mitsui Fudosan UK said more than 100 guests attended the ceremony, including representatives from local community groups, Camden Council and businesses based in the King's Cross Knowledge Quarter. The firm published highlights of the event on its website.

The project received planning permission from Camden Council in July 2024, with construction scheduled to begin in 2026.

Project Scope: 1.04 Million Square Feet

The British Library Redevelopment Project occupies a site of approximately 122,000 square feet, or about 2.8 acres. Total floor area across the redevelopment is approximately 1.04 million square feet. The plans call for an 11-storey above-ground building with one basement level, built with a steel-reinforced concrete structure.

The scheme combines commercial and cultural uses:

• Commercial space: Approximately 600,000 square feet aimed primarily at science, technology, data and life-sciences occupiers.
• British Library space: Approximately 100,000 square feet, including exhibition galleries, learning facilities, event space and business-support functions.

RSHP is the architect and Arup the engineer. Stanhope PLC serves as development manager. The project will preserve underground infrastructure for a potential future Crossrail 2 station connecting the Euston and St Pancras areas, and the developer has committed £23 million toward affordable housing.

Market Context: Tight Grade A Supply in King's Cross

The commercial component is intended to cluster occupiers near institutions including the Francis Crick Institute and the Alan Turing Institute. The site is within roughly one minute of St Pancras Station and three minutes of King's Cross and King's Cross St Pancras stations.

Central London office data for the second quarter of 2026 recorded a 1.61% Grade A vacancy rate in King's Cross, the lowest among the tracked core submarkets. Across Central London, approximately 1.68 million square feet of office space was expected to complete in 2026, with 35% already pre-let or under offer.

Prime Central London rents were approximately £175 per square foot in the second quarter of 2026. Prime rents in the relevant submarket were approximately £95 per square foot and forecast to increase by an average of 5.7% annually over the following five years.

Outlook: Long Delivery Timeline

With completion targeted for 2032, the project's delivery horizon extends across multiple market cycles, leaving the scheme exposed to changes in construction costs, financing conditions, life-sciences demand and London's future office requirements.

Sources

• Mitsui Fudosan UK Limited: A look back at a significant milestone for the British Library extension project