30 Cannon Street (formerly CRédit Lyonnais), City of London, London

Summary

Bank headquarters, 1974-7 by Whinney, Son & Austen Hall (partner in charge Jeremy Mackay-Lewis), structural engineers Ove Arup & Partners.

Description

Bank headquarters, 1974-7 by Whinney, Son & Austen Hall (partner in charge Jeremy Mackay-Lewis), structural engineers Ove Arup & Partners.

MATERIALS: reinforced concrete frame with double-skinned cladding panels of glass-fibre reinforced cement (GRC).

PLAN: 30 Cannon Street occupies a triangular site at the junction of Cannon Street and Queen Victoria Street; the base of the triangle is the narrow Bread Street. The building is of six storeys plus a raised basement. As originally designed, the three external entrances on Cannon Street, Queen Victoria Street and Bread Street gave access to a central circular banking hall, planned around a lift core. The entrance to Bread Street* has since been infilled, an alteration which is not of special interest. The circular design was chosen to provide counter positions of equal importance for up to three banks, whose offices would occupy the three points of the triangle. A suite of conference rooms was located at the centre of the building. The ground floor layout and finishes* has now been entirely altered with the loss of the circular banking hall, and is not of special interest. The basement* contained plant, mainframe computers and a strong room (not of special interest).

EXTERIOR: the external elevations comprise storey-height GRC cladding units on a 1.5m module, off-white in colour and separated by a band of polished black granite. The upper storeys have tapering windows with rounded corners, set between curved fins which lean outwards at an angle of five degrees. On the uppermost storey the units are turned 180°. The raised ground floor is divided by larger pre-cast units into 4.5m bays, three times the upper floor module. Here the glazing is facetted and terminates in a flattened four-centred arch. Below the glazing is a spandrel panel of black granite. Main entrances to Cannon Street and Queen Victoria Street are highlighted by flanking bays which extend the wide ground-floor bays to the floors above. The cantilevered entrance canopies* have been replaced in glass, and these replacements are not of special interest.

At the narrow Bread Street end the need to obtain adequate daylight and to preserve neighbouring properties' 'right to light' led to a section where each storey is set back from the one below. Full-height, facetted window strips are set between flat mullions. Vertical stair towers separate the two designs. The windows have bronze-tinted, double-glazed units in PVC-covered steel frames.

INTERIOR: the interiors have been much altered. The central banking hall was originally finished in travertine, with counters of bullet-proof glass, marble, stainless steel and suede. The central banking hall has since been replaced by a reception area* which is not of special interest. The office floors above were intended for periodic replacement and were originally finished with standard suspended ceilings and floor finishes. The present office floors* are entirely early C21 replacements and are not of special interest. The internal face of the external envelope is clad in GRC panels of similar appearance to those of the exterior. Although the stairs* and lifts* remains, these features have been entirely refurbished and are not of special interest, nor is the plant* and equipment* contained in the basement and mounted on the roof.

SUBSIDIARY FEATURES: The perimeter railings to Cannon Street and Queen Victoria Street incorporate arched shapes of similar appearance to the cladding panels.

* Pursuant to s.1 (5A) of the Planning (Listed Buildings and Conservation Areas) Act 1990 (‘the Act’) it is declared that the ground floor layout and finishes including reception area; upper office floors; stairs; lifts; and basement including plant and strong rooms are not of special interest. Also not of special interest are the infilling of the former Bread Street entrance and the replacement glass canopies to the Cannon Street and Queen Victoria Street entrances.

History

Crédit Lyonnais, one of the major Parisian banks, took the decision to build new premises in late 1972, in advance of the expiry of their existing lease in March 1976. They obtained a lease from Wates Property Company on a triangular island site, occupied by a disused fire station and one of the last bomb sites to be redeveloped in the City of London. An Office Development Permit was granted in January 1973, and the architects (Whinney, Son & Austen Hall), were appointed soon after, leaving an unusually short timetable for detailed design and construction. Construction was divided into two phases, with a requirement to complete the first phase in time for occupation by March 1976. The building was completed ahead of schedule, despite the miners’ strike, three-day working week and the discovery of significant archaeological remains on the site including two medieval churches.

The planning authority had rejected several previous schemes for the site and required a high standard of design. The client wanted a prestige building of sufficiently striking appearance to command its island site and be discernable from a distance. The curvilinear design was developed by Jeremy Mackay-Lewis, the partner in charge, 'over one weekend of concentrated work’, and planning permission was granted four months later, in October 1973. The height of the building was limited by height regulations in the vicinity of St Paul’s Cathedral and a sub-basement was ruled out by the water table, so the minimum lettable floor area was achieved with a raised basement set back from the pavement. The internal area was also boosted by the floor overhangs.

30 Cannon Street is the first building internationally to be fully clad in double-skinned glass-fibre reinforced cement (GRC) panels. The initial choice of cladding was pre-cast concrete, but this was rejected by the freeholder at a late stage. Enamelled pressed steel was then considered, and the architects consulted Jean Prouvé, the authority on this material, but no press was found large enough to manufacture the pre-cast units. Bronze and aluminium were also rejected on grounds of cost and concerns about oxidisation. Fire regulations prevented the use of glass-fibre reinforced plastic (GRP) on a structure of this size. The architects eventually turned to its non-combustible equivalent, GRC.

The idea of adding an ingredient such as glass-fibre to Portland cement to improve its tensile strength had been the long-term aim of research, but a chemically-stable glass-fibre capable of architectural applications was only developed in 1969. The material is obtained by mixing Portland cement with 5% alkali-resistant glass-fibre reinforcement, which forms a matrix easily mouldable to the required shape. It was necessary to determine the structural properties of GRC from first principles, assessing its tensile strength and behaviour under wind loading. Like GRP, inherent strength was increased by incorporating curves in three dimensions, creating a characteristic modelled effect. The GRC units were cheaper, lighter, thinner and less porous than pre-cast concrete equivalents, reducing the costs of the structure, foundations and transport, and permitting more lettable floor area. 1,900 units were manufactured by Portcrete Ltd and delivered to site complete with window frames, leaving only the glass to be fitted in-situ.

Reasons for Listing

30 Cannon Street (formerly Crédit Lyonnais), an office building of 1974-7 by Whinney, Son & Austen Hall, is listed at Grade II for the following principal reasons:

* Architectural interest: an expressive and assured design, its splayed plan, canted profile and high-relief modelling confer the exteriors with a sculptural quality;

* Innovation: the first building internationally to be fully clad in double-skinned panels of glass-fibre reinforced cement (GRC), a form of prefabricated cladding that permits rapid on-site assembly as well as a striking visual appearance;

* Group value: the building has strong stylistic and functional affinities with the Victorian commercial architecture of Queen Victoria Street, and group value through its close proximity and associated design with the Grade II-listed Albert Buildings opposite.

External Links

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