Decorating Carlton House Terrace

Carlton House Terrace was designed by John Nash and constructed between 1827 and 1833 on the site of Carlton House, the demolished London residence of King George IV. When the King moved to the newly remodelled Buckingham Palace, he authorised Nash to develop the Carlton House site as the grand southern terminus of his Via Triumphalis connecting Regent's Park to St James's Park. Nash designed two continuous terraces, each of nine houses, flanking the Duke of York Steps that descend to The Mall. The terraces were conceived as palace facades — unified compositions of giant Corinthian columns above a rusticated ground storey — that would provide a suitably regal backdrop when viewed from St James's Park. The houses were among the most prestigious in London, attracting residents including William Ewart Gladstone, who lived at number 11 during four terms as Prime Minister, and Lord Palmerston, who occupied number 5. During the twentieth century, many houses were converted to institutional use: the Royal Society occupies numbers 6-9, the Institute of Contemporary Arts inhabits the former Nash stables beneath the terrace, and several learned societies and diplomatic missions occupy other properties. The German Embassy was located at numbers 7-9 Carlton House Terrace until 1937, and the Free French forces used number 4 as their London headquarters during the Second World War. The entire terrace is Grade I listed and remains in Crown Estate ownership, subject to rigorous conservation oversight that ensures any decorative intervention meets the highest heritage standards.

The maintenance of Carlton House Terrace's stuccoed elevations represents one of the most demanding decorating challenges in London. The Roman Cement render, being highly hydraulic, has a denser matrix than the lime-based stuccos used on earlier buildings, requiring careful selection of compatible coatings. Keim Mineral Silicate paint systems are specified by the Crown Estate for all stuccoed surfaces, as their chemical bonding mechanism avoids the delamination risks associated with film-forming paints applied to cementitious substrates. The Crown Estate palette specifies a warm Portland stone cream for the rendered surfaces, with the architectural enrichments picked out in a slightly lighter tone to enhance their three-dimensional modelling. Repairs to the Roman Cement must use a formulated repair mortar that replicates the hydraulic properties and colour of the original; proprietary NHL 5.0 mortars gauged with appropriate aggregates can achieve satisfactory results, though specialist conservation contractors may opt for genuine Roman Cement sourced from remaining deposits. The cast-iron columns require periodic inspection for corrosion, particularly at their bases where rising damp can penetrate the stucco cladding; treatment involves localised removal of render, mechanical de-rusting of the iron, application of rust-inhibiting primer, and re-rendering with a breathable mortar incorporating a sacrificial anode where appropriate. Lead flashings at cornices and parapets should be maintained using traditional plumbing techniques, with lead sheet of Code 6 or Code 7 weight employed for durability. The timber sash windows demand a complete linseed oil paint system to maintain the vapour permeability essential to their longevity.