Heritage Statement 30 Grosvenor Square Applications for Amendments to Planning Permission and Listed Building Consent (s.73 & s.19): Lighting, façade restoration and cleaning. October 2020 Contents 1. Introduction 1 2. The Heritage Asset – 30 Grosvenor Square 2 3. Proposed Amendments 7 4. Impact Assessment 11 5. Conclusion 15 Appendix 1: Statement of Significance: Former United States of America Embassy, Grosvenor Square (Grade II listed building) 16 Appendix 2: Policy, Guidance and Advice: Lighting Historic Buildings (extracts) 55 Our reference QATN3001 October 2020 1. Introduction Background 1.1 Listed building consent and planning permission are sought for Amendments to the previously consented proposals (the ‘Approved Scheme’). 1.2 The Amendments comprise: a. Installation of external lighting on all façades of the building, uplighting to the Eagle sculpture and installation of lighting within the landscape including uplighting to trees and building columns; b. Careful temporary removal and storage of the existing column stone cladding and end caps on all façades to facilitate construction works, with material proposed to be securely re-instated with mechanical fixtures; and c. Proposed cleaning of all existing Portland stone that has been retained, including the reinstated stone cladding of the cruciform columns. 1.3 This document acts as an addendum to the original Heritage, Townscape and Visual Impact Assessment (HTVIA) that supported applications 16/06423/FULL and 16/06463/LBC and to the subsequent addendum document, which supported applications 18/03520/FULL and 18/03517/LBC (as amended). 1.4 The requirement for this assessment derives from the Planning (Listed Buildings and Conservation Areas) Act 1990 that places a duty upon the local planning authority in determining applications for development affecting listed buildings to pay special regard to the desirability of preserving the building or its setting. 1.5 The National Planning Policy Framework (NPPF) provides the Government’s national planning policy on the conservation of the historic environment. In respect of information requirements for applications, it requires that: “In determining applications, local planning authorities should require an applicant to describe the significance of any heritage assets affected, including any contribution made by their setting. The level of detail should be proportionate to the assets’ importance and no more than is sufficient to understand the potential impact of the proposal on their significance”1 1.6 The nature and extent of the significance in terms of special interest of the listed building, the contribution of setting and the significance of the wider Mayfair Conservation Area and adjacent Grosvenor Square registered park and garden were fully assessed to support the previously consented applications. 1.7 For ease of reference, the full assessment of the significance of the listed building is set out in Appendix 1 drawn from the Heritage Townscape and Visual Impact Assessment (HTVIA) which supported the previous applications. 1 National Planning Policy Framework (NPPF) 2019 1 2. The Heritage Asset – 30 Grosvenor Square Introduction 2.1 The former United States of America Embassy (30 Grosvenor Square) was added at grade II to the statutory list of buildings of special architectural or historic interest on 21st October 2009. The building was built 1957-60 to the design of Eero Saarinen assisted by Yorke, Rosenberg and Mardell as UK executive architects; F J Samuely were the structural engineers; and, the Eagle statue was by Theodore Roszac. 2.2 The building is located on the west side of Grosvenor Square, with shorter return elevations to the north and south set back from the street, from which it was separated by a stone faced glacis. The building has a symmetrical ‘U’ shaped plan, comprising a raised ground floor with central main entrance and lobby with large halls to either side, leading through to single storey offices. 2.3 Separate entrances to the former Consular and Information Sections are on the north and south sides, each with a lobby and stair to either side. The basement comprised a café and auditorium and the upper floors were cellular offices. 2.4 Constructed of reinforced concrete clad in Portland stone on the front and side elevations and concrete to the rear, the long tripartite façade comprises 22 bays with 5 bay entrance and tall recessed ground floor supported on cruciform columns, with 4 floors and set back attic storey above. 2.5 These upper floors are carried on a giant concrete ‘diagrid’ floor of intersecting diagonal concrete beams the exposed ends of which enable the façade to overhang the column line. Several external elements including the exposed ends to the structural diagrid were clad with aluminium. 2.6 The full history, development and resultant significance of the building in terms of special architectural or historic interest is set out in Appendix 1 to this Addendum. Summary of Heritage Significance 2.7 For national planning policy purposes, heritage significance is defined2 “as the value of a heritage asset to this and future generations because of its heritage interest. That interest may be archaeological, architectural, artistic or historic. Significance derives not only from a heritage asset’s physical presence, but also from its setting”. 2.8 The grade II listed former Embassy building is a designated heritage asset3 and significance as a listed building derives from special architectural or historic interest4. 2.9 The list entry description whilst prepared before the provisions of the Enterprise and Regulatory Reform Act 2013, is nevertheless clear regarding the reasons for listing of 2 NPPF Annex 2 Glossary 3 Ibid 4 Section 1 Planning (Listed Buildings and Conservation Areas) Act 1990 2 the building and precise regarding the nature and extent of special interest. Subsequent visits to the building by Historic England’s listing team5 did not highlight any other substantive areas of perceived interest within the building to those noted at the time of listing. 2.10 Notably, at the time of listing English Heritage (now Historic England) stated6: “The special architectural interest of this building lies primarily in its strongly- articulated design and dynamic facades. The design employs an innovative application of exposed concrete diagrid. The internal interest of the embassy is largely confined to the ground floor, the ceilings echo the diagrid formula of the building’s façade and the central lobby is clad in Greek Pentelicon marble. This constructional form (of unusual sophistication in 1950s Britain, showing the technological prowess then associated with the United States) is one of the building’s principal features, expressed externally and internally and echoed in details such as the gilded pressed-metal parapet and the cog- wheel window motifs and exposed beam ends.” 2.11 A full assessment of the significance of the listed building is set out in Appendix 1 drawn from the Heritage Townscape and Visual Impact Assessment (HTVIA) which supported the previous applications. In summary: Special Architectural Interest: Strongly articulated design and dynamic facades with well-detailed stonework and consistency of detail; Of particular note, the exposed concrete diagrid – an intelligent combination of structural expression and decorative motif, provides cohesion to the whole and illustrates architect’s principles of marrying from to structure, interior to exterior, and his close involvement in detail and execution; Building designed by Eero Saarinen - an outstanding figure in C20th architecture and design – and provides early example of a modernist yet contextual approach to design in a sensitive urban location; Eagle statue by Theodore Roszac, noted Polish-American sculptor. Executive UK architects Yorke, Rosenberg and Mardell and F J Samuely structural engineers (Frank Newby); Internal interest (confined to ground floor public spaces): main entrance and central lobbies, passport office and former library (with cruciform columns) and former information service and consular lobbies and stairs where the diagrid is exposed throughout. The most notable area is the central lobby clad in Greek Pentelicon marble. 5 April 2015 6 English Heritage press release 22nd October 2009 3 Special Historic Interest: Strong associations with Grosvenor Square (home of first United States Ambassador to this country (No.9) and nerve centre for American Armed Forces and headquarters for General Eisenhower in Great Britain in World War II (No.20) – commemorated by monuments (gardens re-planned in memory of F D Roosevelt, grade II listed statue of Roosevelt). Britain’s first modern embassy building – international significance as the apotheosis of United States post-war embassy building programme; only one the result of architectural competition; exemplifies United States post-war mission to engender good will to host nations and buildings that harmonise with surroundings yet distinguishably American and accessible. Embodying the special relationship between the United States and United Kingdom also a target for anti-US sentiment – most famously in 1968 anti- Vietnam war demonstrations. 2.12 Noting that external architectural interest diminishes with the rear elevations, which are clad in concrete rather than stone, with the two wings infilled a lower single storey block with service bays beneath, added in place of the originally intended open courtyard in order to provide more office space.