Open House London: Exploring 75 Grosvenor Street and its amazing roof gardens

Open House London is an annual architecture festival that allows us to go inside buildings that are often unavailable to the public. I like to visit a variety of places which is how I discovered this Mayfair office. You could walk past and think it’s just another row of Georgian townhouses but going inside, I saw the incredible work of the developers transforming three buildings into one.

Three Buildings Into One

Grosvenor Street was one of the earliest streets to be laid out as part of the Grosvenor family’s development of their Mayfair lands. In 1735 Grosvenor Street was described as ‘a spacious well built Street, inhabited chiefly by People of Distinction’. (Robert Seymour, A Survey of the Cities of London and Westminster, vol. II, 1735, p. 666.)

Nos. 72 to 81 were renumbered in 1866.

75 Grosvenor Street is actually nos. 73, 74 and 75 brought together.

Nos. 73 and 74 Grosvenor Street were built in the early 1700s as matching townhouses. No. 75 was built as a narrower, single house. The houses provided London accommodation for provincial nobility during the court season and parliamentary sessions.

No. 73 (formerly No. 72) Grosvenor Street was originally built in 1724 with four windows wide and three stuccoed stories above a modern shop front.

No. 74 (formerly No. 73) Grosvenor Street was built in 1722 as a four-story stuccoed house. It was four windows wide, with a Doric portico. It was likely the same bricklayer who built both nos. 73 and 74.

No. 75 was built in 1914 by George Trollope and Sons to the four-story, neo-Georgian red brick design of Edmund Wimperis, the estate surveyor, and his partner, William Begg Simpson. It was the third house on the site from the original Grosvenor Estate development. The first was built before 1725 by Thomas Barlow, carpenter, who was also the estate surveyor.

In 1906 the then estate surveyor Eustace Balfour, who admired its ‘original entrance doors and staircase’, wasn’t keen for the building to be removed. But by 1912 Wimperis had succeeded him, and the replacement of what he called an ‘old and badly arranged house’ was approved. The original doorcase was re-used and is a particularly fine example with elaborately carved brackets.

The project also included the demolition of the six-story building at 31-33 Grosvenor Hill at the rear of the site. The site is in the Mayfair Conservation Area.

Earlier Refurbishments

In 1838–40 and again in 1851 alterations were made to no.73. John Elger, the builder, was probably responsible, at a later date, for raising the house by an extra story. The shop front was installed by Collcutt and Hamp in 1928.

In 1849, no. 74 was raised by an extra story and the façade was altered to the designs of Thomas Cundy II, the estate surveyor. The portico and balcony were added in 1872, replacing the original flat Doric doorcase.

Cundy’s elevation was part of a major scheme of remodeling undertaken in 1849–50 for the Devy family, who combined the businesses of silk mercer, milliner and court dressmaker. The ground and first floors were converted into offices and a small wing at the back was rebuilt to provide domestic accommodation.

Since that date, the building has undergone three separate refurbishments. The Grosvenor Estate reverted no. 74 to residential use in 1872 and then into use as practices of important physicians, as well as being home to Thomas Lovell Buzzard during the early 1900s, a pioneering neurologist who founded the Epilepsy Society.

In 1948, no. 74 became an office and showroom and in 1996 it was turned once again into offices.

Grade II Listed

Nos. 73 and 74 Grosvenor Street are individually listed Grade II. No.75 is not listed. Grade II listed means they must be preserved but it doesn’t mean they were in their original state. Both properties had been altered and extended over the years.

Due to the Grade II listed status, a lot of conservation and restoration was needed as well as new construction to bring the three properties together as a single, coherent, office building. Every small change to a listed property needs approval which extends the planning and preparation time considerably.

Accessibility

While the accessibility has been improved with central lifts, there are still areas of the building that cannot be wheelchair-accessible and that is permitted for these older properties.

Grosvenor Estate

The three buildings were not in the greatest condition so the Grosvenor Estate was interested to hear from developers. The Grosvenor Estate owns most of the streets in Mayfair and Belgravia. The Duke of Westminster is the Chair of the Trustees of Grosvenor Estates. Their offices are next door so the project was carefully overseen.

Seven Years

This has been a 7-year project. The first 3+ years were for the planning negotiations and 2.5 years on site. Over 1000 people responded to the public consultation which shows the level of interest in these changes. Planning permission was granted in 2016/17 and the project was completed in October 2021.

Sensitive Redesign

W.RE – the developer behind this transformation – has considered the historic features and Cowie Montgomery – the architects – has used creative architecture to reconfigure the space. Columns have been removed and floor levels adjusted to create additional stories. (The floor-to-ceiling height varies in the historic buildings.) There are now seven floors with nearly 37,000 sq ft of office space, plus five outdoor terraces and a beautiful central staircase.

The façade and balconies have been redesigned so they remain in context with the buildings’ original character, while modern terraces and green roofs offer occupants amazing views over Mayfair.

It is an L-shaped building. Only one of the bays is on Grosvenor Hill at the back as no.77 wraps around the building. On an interesting topographical note, Grosvenor Hill at the rear is a whole level lower than Grosvenor Street.

The view from the street is unchanged but inside is where the magic has happened with the new creative and elegant modern architecture. It’s quite the white, blank canvas at the moment while negotiations are underway with prospective tenants. But clues to the buildings’ past can be found throughout the historic and modern spaces.

Careful consideration was taken to preserve the historic features and showcase the Georgian heritage. Twenty-seven fireplaces have been retained with the more ornate fire surrounds on the lower floors, as there always would have been.

It was within no. 74 that the majority of the preservation work took place. The building contained listed brick walls, original listed staircases and chimneys, and two original listed fireplace surrounds. These were restored on and off-site so they can be repurposed as features of the new office space.

As well as fireplaces, door surrounds, cornices, etc on display from the original structure a couple of other features have been left exposed from the renovation. Within the original walls, was a wooden frame that was then filled in with bricks and mortar. A wooden frame section has been left in one office so you can see the timber. Changes were made over the centuries but most of what is on display is original.

And on the second floor, there is a wall of exposed brickwork. The developer explained that these features were only left open when they added to the overall design. On this wall, you can see the 1720s bricks and wooden frame.

Past Residents

No. 75 was home to Baroness Spencer-Churchill, Winston Churchill’s wife, who was born on the premises on 1 April 1885 as Clementine Hozier.

Alister Maynard MBE, a talented 20th-century artist who designed interiors for Kensington Palace, The Dorchester and The Connaught was a resident of No.73.

The former Estée Lauder headquarters were at 73–75 Grosvenor Street.

On the first floor, there are a couple of previously undiscovered eighteenth-century portraits that provide a glimpse into the lives of the Georgian townhouses’ former residents. These have been researched and it was discovered that, in the 1760s, a portrait customer would choose a painting ‘off the shelf’ and simply have their face added to the body. The customer could pay extra to have a family emblem added. So you may well see very similar paintings elsewhere.

The Devy family of Royal couturiers and silk merchants lived and traded here in the nineteenth century. In a nod to this history, in the atrium/lightwell there are interlayered silk glass panels that can be seen between each level, and also cladding the new lift core.

Neighbours

While the Grosvenor Estate London headquarters is on one side, on the other is an office block that was built in 1938–40. Although basically adhering to Grosvenor Estate’s favored neo-Georgian tradition, the bow windows and shade of brick do make it clear it’s more modern.

The building that was demolished for this replacement was the London home of brothers and business partners, architects Robert and James Adam from 1758 until 1772. In January 1758 Robert Adam returned from the Grand Tour and took the house shortly afterwards, having realized that a fine house in London would be needed ‘to blind the world by dazzling their eyesight with vain pomp.’

Atrium

The atrium and link bridges were the most contentious element of the proposal. The lightweight atrium structure sits a story below the parapet height of the rear of the listed building, reducing its visual impact in longer views.

The link bridges are in steel and glass. Whilst totally contemporary, it was suggested that the lack of existing historic detail in this area reduces the potential for harm.

Although this is an excellent area to view the restored rear historic facade.

Green Roofs

The scheme incorporates two green roofs: one on the fifth floor behind 74/75 Grosvenor Street and one on the fourth floor between no. 73 Grosvenor Street and 31-33 Grosvenor Hill.

I also got to admire the ‘Mary Poppins rooftop view from one of the balconies.

I am unsure of the reason for the lower level around the edge of the balcony flooring. Possibly for drainage? To me, it looked like an ankle-twisting issue waiting to happen.

Feature Staircase

In the center of the building is a £1 million feature helical staircase. It spans five floors and was designed by EE Stairs. The solid steel staircase was imported from Holland. The staircase is not a round spiral; it’s more of an oval to fit the space.

Helical staircases are fabricated to have the appearance of a curve or helix. This curved structure leads you from one level to the next by way of a flowing circular rotation.

From the entrance hall, one of the 300-year-old Hanoverian staircases is restored and in use.

Bespoke Design

The design on the new limestone floor at the front entrance is a bespoke motif intended to be representative of the crests of eighteenth and nineteenth-century livery companies. The design is repeated on the air grilles, façade metalwork, and internal balustrades – weaving a thread of the past throughout the building.

Lower Ground Level

The rear of the building has a bike entrance with bike storage and drying rooms. The flooring is worth noting as it is end block wooden flooring that would have been used for London streets in the past.

There are luxurious male and female washrooms with showers and lockers.

As the tenants of this building will be at the premium end of the real estate market, there is consideration taking place on whether the open space on this level should be a professional kitchen for in-house dining, or maybe a gym or wellness zone.

Best Materials

As well as using traditional materials in the restoration, the new interior design materials are of the highest quality. There is dark oak herringbone flooring in some of the office space and the lift doors are faced with bronze. The lower-ground marble washrooms are reminiscent of a luxury hotel spa.

Sustainability

A lot of sustainability in the construction industry is about not demolishing old buildings and replacing them with new. It is now about repurposing old buildings. For the extension here, all of the structural elements were reused.

Thermal performance was prioritized to ensure this project was a net-zero carbon development. Sustainable materials were used to support this including green roof space. The restored sash windows are still single glazed but, overall this project reached a BREAAM ‘Very Good’ standard.

Address: 75 Grosvenor Street, Mayfair, London W1K 3JS

Official Website: 75grosvenorstreet.london