The Hanging Gardens of Basingstoke – ADC

Plant, Basingstoke, a landmark of 1970s British modernism originally designed by Peter Foggo and Arup Associates Group 2 has been brought back to life. With planning and listed consent given to Grant Associates and Feilden Clegg Bradley Studios’ initial design, Twelve Architects and Studio Knight Stokoe took the scheme forward to complete the building’s transformation.

First known as Gateway House and later Mountbatten House, the building, completed in 1976 for paper manufacturers Wiggins Teape, is a six-storey terraced office complex celebrated for its architectural and horticultural significance. Its innovative hanging gardens, designed by James Russell, and its bold modernist structure earned the building separate listings by English Heritage in 2015.

The retrofit restores and reinvigorates the 19,515-square-metre office complex as a regional hub for Hampshire’s economy, capable of hosting multiple tenants. Led by client William Laxton of Mactaggart Family & Partners with developer Longstock Capital, the £32 million project reflects a deep respect for Foggo’s original vision and the lush, cascading terraces that make the building unique.

“The building design’s prescience in creating contact with, and access to, nature within all the office spaces on all levels created a legacy that even now appears forward thinking,” said Ian Taylor, partner at Feilden Clegg Bradley Studios.

“While significant replanting was necessary due to the deteriorated condition of the gardens and soils, this provided an opportunity to reinforce the essential balance between the Grade II Listed building and the restored landscape,” added Martin Knight, director at landscape architects Studio Knight Stokoe speaking to Architecture Today.

“The original design was notably progressive in integrating architecture with landscape, particularly in the generous allocation of garden space. A key focus remained on maintaining the intentional contrast between the clean, modernist lines of the extensive glazing and anodised aluminium facades and the informal, overflowing character of the gardens.”

The building’s entrance and reception area have been reconfigured, now including a striking helical staircase inside a double-height space that improves visual connection to the verdant surroundings. Meanwhile, the refurbished curtain wall system enhances thermal performance without compromising the architectural character, with mechanical, electrical, and plumbing systems also being modernised to future-proof the space for evolving tenant needs. New amenities have been added too, including a cafe, gym, secure cycle storage, and flexible event spaces, meeting contemporary expectations for workplace wellbeing.

On the building’s terraces, Foggo’s original coffered slab structure and cruciform columns have been uncovered, revealing the structure’s bold geometry. A new contemporary water feature has replaced a deteriorated pond too, bringing a sensory layer to the cloistered courtyard on the second level, while winding pathways and intimate seating areas encourage exploration, offering moments of respite and reflection for users.

To retain Foggo’s distinctive terrace design, all paving and step elements of the gardens, including yorkstone slabs, bespoke concrete panels, and bespoke concrete steps, were numbered. Each element’s position was also recorded using aerial photography with its number being included on detailed plan drawings. After being carefully removed and placed in storage while works could take place, these paving and step elements were eventually put back according to their original position.

Plant’s showpiece, however, is the flora draped around it. Drawing from archival research at the University of York, including James Russell’s planting lists, the gardens have been adapted to withstand rooftop conditions while enhancing biodiversity. More than 22,500 plants and 86 new trees join the existing flora, creating a climate-resilient landscape that supports inhabitant wildlife.

“The flexibility within James Russell’s overarching vision provided scope for adapting the planting scheme while remaining true to each garden’s unique theme,” continued Knight. “A complete audit of the original handwritten planting palettes and plans assessed which species or varieties would suit current and anticipated climate conditions, while supporting biodiversity and foraging habitats for pollinators and fauna.”

Studio Knight Stokoe’s planting strategy ensures even load distribution across the structure, a feat achieved through close collaboration between themselves, structural engineers Whitby Wood and soil specialists Tim O’Hare Associates, the latter designing in new soil profiles.

“Adapting the planting to rooftop conditions involved complex structural and soil management challenges. Due to extremely poor site soil conditions, complete stripping and replacement was necessary,” said Knight.

“The dual constraints of structural loading capacity and limited planting substrate depths shaped the approach to plant selection. Heavier landscape elements were concentrated around building columns, with free-draining soil profiles and drought-tolerant plants preventing water saturation from stressing the structure.”

Native and non-native planting varieties have been added as part of a “systems-based approach” that focuses on soil profiles, minimal automatic irrigation from collected rainwater, and ecological habitat enhancements for pollinators and foragers.

As part of this, drought-tolerant planting works alongside free-draining soils to be able to deal with heavy rainfall and extreme heat events with minimal irrigation being required.

Energy efficiency measures such as solar photovoltaic panels and low-energy systems have been added as well, while the adaptable design allows for future modifications with minimal environmental impact.

Despite the project’s listed status limiting changes that could be made to the building’s envelope, Plant has achieved BREEAM ‘Outstanding’ and WELL certification. Improvements to external glazing was curtailed to upgrading the original double-glazed units with much of the original framing being retained.

“For WELL Certification, this meant points for Operable Windows and Enhanced Operable Windows could not be pursued,” explained Knight. “Additionally, some daylighting criteria points were unattainable due to the existing building layout, including deeper floorplates in certain areas that fell outside the ideal parameters.”

Above, on the building’s extensive roof terrace, thermal upgrades were also impractical due to the fact they would disrupt retained planting and compromise existing finish levels.

Since the project has completed, Studio Knight Stokoe has been monitoring the gardens progress since being established on the site. As they develop and grow, adaptions will be made in accordance with seeing which species thrive or struggle in the new habitat.

“The project team has captured the original spirit of Plant and delivered an outstanding refurbishment,” said Hugo Denee, co-founder of Longstock Capital. “Plant is a unique building that we are all immensely proud of, and will serve the region for many more years to come. The building is now a perfect example of what occupiers require in terms of design aesthetic, environmental credentials and amenities and the proof is in how well it has been received by the leasing market.”

“It’s wonderful to see how the refurbishment has enhanced natural light, spatial flow and brought tenants closer to nature,” Robert Shannon, associate director at Twelve Architects & Masterplanners added. “With sustainability at its core and BREEAM ‘Outstanding’ certification, Plant sets new standards for the future of office design. It has been a privilege to work with such an outstanding team and a client who is truly passionate about delivering remarkable buildings.”

Keith French, director at Grant Associates, also comment: “Our approach in helping to bring this amazing building and series of gardens back to life, has been to honour the original vision of seamlessly blending architecture and landscape. This project provided a unique opportunity to not only preserve the legacy of Peter Foggo and James Russell but also to enhance it for future generations. By prioritising nature, wellbeing, and sustainability, as a team we’ve created an environment that reflects the changing needs of the modern workplace while staying true to the building and garden’s pioneering spirit.”