Plant, Basingstoke

Andy Stagg

Revitalised 1970s modernist office and gardens foster a sustainable environment where occupants and nature can flourish

• Architect (RIBA 4–7), Principal Designer

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Twelve Architects & Masterplanners and Studio Knight Stokoe have completed the heritage-led retrofit of a Grade II listed 1970s modernist office building in the town of Basingstoke, Hampshire, England. The newly renamed Plant building, formerly known as Mountbatten House, fosters a sustainable environment in which both occupants and nature can flourish.

A significant post-war office building

Mountbatten House, originally named Gateway House, was commissioned in 1973 by the then paper manufacturer Wiggins Teape as its new headquarters (it was constructed from 1974–76). The building, designed by Arup Associates Group 2 and led by English architect Peter Foggo, exemplifies their innovative and sustainable approach to the built environment. The distinguished English garden designer James Russell advised Arup on the building’s large-scale garden design. An expansive, stepped complex, Plant comprises six levels of commercial workspace with a sweeping blanket of tiered roof gardens and terraces.

In 2015, the building and its gardens were listed separately by English Heritage. Historic England has recognised Mountbatten House as one of the most significant post-war office buildings in the UK.

A collaborative endeavour

Plant offers more than 19,515 square metres of category A and B office and amenity space. The client, William Laxton of Mactaggart Family & Partners (a UK-based private investment firm), was attracted to the scheme because of the original Peter Foggo design and the abundance of terracing, making it a singularly unique building.

The revitalisation of Mountbatten House, which involved restoring the building’s original design intent, creating a harmonious blend of workplace, nature, and well-being, was a significant collaborative endeavour. Twelve Architects and Studio Knight Stokoe worked closely with the client, developer, and contractor to complete the design by architectural studio Feilden Clegg Bradley Studios and landscape architect Grant Associates.

Minimal structural interventions with noticeable revisions

Plant is targeting BREEAM Outstanding and WELL Platinum certifications.

The project placed an emphasis on minimal structural interventions to the building. To preserve the building’s architectural character, its facade frames, travertine, and engineering brick wall finishes were retained. Noticeable revisions include a redesign of the entrance and reception area by London-based Page Architects. This has enhanced the arrival experience, establishing a strong visual connection to the verdant refurbished gardens. The introduction of double-height spaces establishes vertical connections between floors, enhancing the sense of openness and inviting more natural light into the building. A helical staircase links the reception area to the second level.

The removal of recently installed suspended ceilings and finishes has unveiled the building’s distinctive coffered slab structure and cruciform columns, preserving its unique architectural character. The original curtain wall system has been carefully refurbished, enhancing the building’s thermal performance and ensuring its longevity. To help Plant achieve a BREEAM Outstanding certification, the mechanical, electrical, and plumbing systems have been fully upgraded, increasing operational efficiency and safeguarding the building’s long-term sustainability.

With the modern-day expectations of workplace tenants, an array of new facilities have been added. They include a cafe, gym, shower and changing rooms, secure bicycle storage, and a multi-purpose function space.

“Hanging Gardens of Basingstoke”

From the original Gateway House to Mountbatten House and now Plant, the building is still affectionately known as the “Hanging Gardens of Basingstoke”. A key driver of the project was to significantly enhance access to the gardens and roof terraces — new level access from all storeys allows greater use and enjoyment of these areas.

Extensive research of archives at the University of York, including James Russell’s comprehensive handwritten plant lists, has ensured that the Grade II listed roof gardens and landscaping are now climate resilient and regenerative. An in-depth analysis of the historic planting palettes was conducted. Plant species that are ill-adapted to exposed rooftop conditions have been replaced by native and non-native plants that are drought tolerant, suited to open conditions, and require minimal irrigation. This fosters improved biodiversity, helping pollinators and foragers to flourish.

Over 22,500 new plants were introduced as part of the project, together with 86 new trees that complement the existing trees on the site. The landscape scheme delivers a 12.79 percent biodiversity net gain.

Without raised planters across the gardens, the landscape architects, structural engineers, and soil specialists collaborated closely to adapt the planting, ensuring even loading across the multi-level structure. The renewed planting design draws inspiration from the original design vision for the gardens: to be informal, elaborate, romantic, overflowing, and tumbling.

Regenerative and biophilic design

Studio Knight Stokoe employed regenerative and biophilic design principles, ensuring the connection between people and nature was not an afterthought. The studio restored much of the existing hardscaping: the original paving elements across the garden levels were recorded and catalogued, temporarily removed during the construction phase, and then replaced in situ. The revitalised gardens create a mix of quiet and communal spaces for the building’s occupants and visitors. In the cloistered level 2 courtyard, a pond in a state of disrepair was replaced with a sculptural water feature that honours the original form, imbuing the space with a fresh sensory experience. Winding pathways and new seating areas offer opportunities for exploration, socialising, relaxation, and quiet reflection.

Plant, a widely regarded exemplar of British modernism and commercial horticulture, is now embarking on a new chapter as a regional hub for growth, fostering an environment in which both occupants and nature can flourish.

RIBA Plan of Work

Planning approval and listed building consent was obtained by Feilden Clegg Bradley Studios; the studio also monitored planning and listed building issues during construction. Twelve Architects completed stages 4 to 6 of the architectural design, including design variations under approval of conditions.

Grant Associates designed the landscape to stage 4. The studio obtained planning approval and listed consent in 2019, and provided a client monitoring role during construction. In 2024, Studio Knight Stokoe obtained planning and listed building consent for an amended landscape scheme, based on the principles outlined in the design by Grant Associates. Studio Knight Stokoe then completed the amended design.