At 34 Portland Place, a major objective is to recover the legibility and hierarchy of the original townhouse. The proposals include the reinstatement of principal rooms, removal of unsympathetic later subdivisions, recovery of historic openings and improvement of the relationship between principal and subsidiary spaces. A Georgian enfilade is being restored, individual principal rooms are being returned to their original proportions and lost architectural details are being reconsidered using documentary evidence. The project also proposes a historically appropriate fireplace where one had been entirely removed and the reinstatement of an Adam-style ceiling for which archival evidence survives. The objective is not stylistic reproduction for its own sake. It is to restore architectural hierarchy where evidence makes that restoration defensible.

Fire engineering is one of the project's most technically significant workstreams. Although the primary project comprises 34 Portland Place and 73 New Cavendish Street, the historic means-of-escape arrangements connect the scheme directly with 36 Portland Place, meaning that life-safety strategy, neighbouring interests and implementation sequencing extend across three buildings. The existing reciprocal escape arrangement between 34 and 36 Portland Place is proposed to be removed and the original separation between the properties reinstated, requiring coordination not only with the project's own fire engineers and Building Control adviser but also with the Freeholder, neighbouring occupiers and separately appointed fire advisers reviewing the adjoining property. Conventional compliance solutions can themselves create significant harm in historic buildings, so the fire strategy also considered alternative suppression systems and the consequences of introducing extensive new pipework through important ceilings and decorative fabric. The design team progressed a water-mist suppression strategy as an alternative to conventional sprinklers, supported by enhanced compartmentation, protected escape routes and performance-based justification. By February 2026, Building Control had indicated in-principle acceptance of a water-mist approach subject to the required technical and heritage justification, and the project has continued independent specialist review of this position, including an additional fire-regulations meeting in August 2026 to verify the proposed approach and its regulatory basis.

The Party Wall work has become a project in its own right. A specialist Party Wall surveyor was appointed at an early stage, and potentially notifiable works were mapped across the complex before construction information was complete so that neighbour engagement could begin without creating avoidable programme delay. The assessment considers numerous interfaces, including basement works adjoining neighbouring properties, work affecting party structures, new and altered structural openings, stair construction, drainage and service routes, removal and infilling of historic connections, means-of-escape alterations between 34 and 36 Portland Place, removal of significant existing steelwork, lift and lift-pit works, roof-level interfaces, and works within the influence of neighbouring structures. The Party Wall consultant's formal review identifies several different statutory triggers and multiple adjoining ownership interests requiring consideration. The neighbouring-property work extends beyond serving statutory notices. Certain design matters depend upon cooperation between the Contracting Authority, Howard de Walden Estate, adjoining leaseholders and occupiers - in particular the historic means-of-escape relationship with 36 Portland Place, which requires improving fire safety, reinstating the proper physical separation of the historic buildings and avoiding prejudice to the operation of the neighbouring school. We are not merely preparing Party Wall drawings; we are managing the architectural consequences of adjoining ownership, occupation and legal rights.

The Howard de Walden Estate is the Freeholder of the site, so a separate Licence to Alter process sits alongside the Westminster planning and Listed Building Consent process. Cohanim has been coordinating information - architectural drawings, fire and means-of-escape information, technical proposals and matters affecting adjoining properties - so that statutory and Freeholder reviews can progress in parallel rather than sequentially. The project reports record continuing Freeholder review, board approval requirements and fire-safety review as active project dependencies.

The scheme requires detailed planning and Listed Building Consent engagement with Westminster City Council. Pre-application engagement included an officer site visit in April 2025, with the developing proposals viewed positively and historic precedent identified for elements of the proposed fenestration. The project then encountered an unusual external challenge when Westminster's systems were affected by a significant cyber incident, delaying access to internal planning records and contributing to an extended pre-application and validation process. Rather than allowing the application to stall, Cohanim maintained direct officer contact, reissued information where necessary, assisted with document access and continued to press for formal engagement, culminating in direct meetings between Westminster, the Contracting Authority and the design team during 2026. The project has also involved specialist heritage consultees outside the Local Planning Authority. The Georgian Group visited the site and formally commended the high level of research and detail provided in relation to 34 Portland Place, recognising the heritage benefits of the wider restoration scheme and supporting the replacement of later windows with more historically appropriate alternatives where the evidence demonstrated that the existing windows did not contribute to the building's significance. Historic England has also formed part of the statutory-consultee strategy.

Health and safety investigation began during the earliest project stages. The specialist consultant register includes Eton Group for management survey work and damp / mycological investigation, and the project archive contains dedicated management-survey, mould-survey and asbestos-remediation documentation. This work has allowed hazardous materials, moisture, mould and existing-condition risks to be considered as part of the design rather than being left as contractor-stage surprises. The early action records also show investigation of historical asbestos records, confirmation of previous remediation, consultation with hazardous-material specialists and separate damp / mycological appointments from the opening weeks of the project.

Existing listed buildings rarely conform neatly to modern drawings, so structural design has developed alongside surveys, opening-up and continuing site verification. The Stage 4 work includes new and altered openings, local strengthening, riser interfaces, roof structures, lift shafts and pits, existing steelwork, basement interventions and the relationship of new services with historic structure. Many of these elements simultaneously engage heritage and Party Wall considerations. The project is consequently being designed iteratively: survey, model, inspect, coordinate, verify and then detail.

The existing services had reached or passed the end of their practical operational life. A complete services strategy has therefore been developed across mechanical, electrical, public health, lighting, fire alarm, security, suppression, gas, water and associated systems. By August 2026, the architectural review register included coordinated packages for lighting and fire alarm, mechanical services, public health and water, schematics, small power, gas, security and sprinkler services. Rather than simply lowering whole ceilings to accommodate ductwork, the design team has repeatedly reviewed service routes, perimeter zones, localised bulkheads and plant positions to protect ceiling heights in the principal spaces - an approach documented in the February 2026 progress record across reception, office and multifunctional rooms, including localised service zones designed specifically to avoid unnecessary reductions in ceiling height. The objective throughout is to use later voids, less significant fabric and existing service zones wherever possible so that improved performance does not come at the expense of the historic interiors.

Inclusive access is another major part of the project. The wider strategy includes accessible WC provision, improved entrance arrangements and new lift infrastructure. At 73 New Cavendish Street, a new passenger lift is proposed within later fabric to provide substantially improved step-free circulation while reducing the impact upon significant historic material. Lift works have required their own coordination across structure, Party Wall considerations, Building Control, fire strategy and specialist lift design.

The project has also required detailed work on infrastructure which is largely invisible in the final architecture. CCTV drainage investigation, roof-water surveys and physical inspections have been used to establish existing routes, condition and reuse potential. Further coordination has included UK Power Networks capacity and connection requirements, water-service upgrades, gas-service upgrades, roof drainage, public-health services and the responsibility interfaces between utility providers and the future contractor. The June 2026 project record confirms continuing water, gas and power coordination alongside the principal Stage 4 design.

The project also has a governance layer which is unusual for a conventional private refurbishment. Cohanim works within a consortium and reports to an overseas governmental Contracting Authority. Project information has consequently been prepared and managed across UK statutory requirements while also responding to the Contracting Authority's own governance and procurement procedures. Substantial project packages have been issued in English and Polish, with controlled repositories, formal progress reports, action logs, drawing registers, meeting minutes and contractual reporting. Procurement documentation has also required coordination with Polish and European procurement requirements alongside UK construction and statutory processes.

The project is unusual in having to accommodate formal diplomatic representation, private residential life, working offices and public-facing cultural activity within the same connected estate. That affects almost every discipline. Security, fire strategy and circulation must distinguish public, staff, guest and private areas. The representative spaces at 34 Portland Place must retain the architectural formality of the historic house while functioning for contemporary diplomatic events, while the Cultural Institute at 73 New Cavendish Street must accommodate public engagement, exhibitions and multifunctional uses while sharing infrastructure with secure diplomatic functions. The design therefore needs to work at both ceremonial and everyday scales.