[7] In 1804, Henry Drummond commissioned his friend the architect William Wilkins to transform his brick house into a neoclassical Ancient Greek temple.

On 6 November 1819, Baring ordered from the Birmingham ironmasters Jones & Clark two metallic pine houses to be built in the new walled kitchen garden on the opposite side of the lake about half mile south east of The Grange.

Designs were ready by June and included an elegant dining room (now demolished) and orangery conservatory (approx 80‘ x 50’) with a four-columned Ionic portico on its east elevation.

There were two large rectangular planting beds running the length of the building with a central and an outer walkway all the way round, paved in Portland stone.

Slim hollow cast-iron columns held up the roofs and channelled rainwater into a large reservoir under the portico which supplied the house and the conservatory.

The vestibule inside the east end of the conservatory had standing boxes of orange trees, camellias, proteas and magnolias which were brought out onto the terraces for the summer (picture).

In January 1827 Jones & Clark wrote to Baring “We think we may safely venture to affirm that the conservatory at The Grange is not surpassed by anything of the kind in the United Kingdom.”[citation needed]“The whole of the conservatory, with the exception of the brick and stone work, was executed, and its different parts put together at our Birmingham and aftwards [re-]erected in its present situation by our own workmen.”[citation needed] This use of prefabrication was revolutionary and a precursor to Paxton's Crystal Palace.

[11] In 1890, Francis Baring, the 5th Lord Ashburton, sold Bath House in Piccadilly, and to accommodate his paintings, converted the orangery into a picture gallery which doubled as a ballroom.

The interior and planted beds were removed and the walls were plastered and fitted with oak dado panelling and a new flat partly glazed ceiling inserted.

In the October 1935 edition of Antique Collector it was stated that The Grange “which seemed doomed to become derelict” had “during the last 18 months been transformed into a palace of art treasures entirely fitting its former glory”.

[12] In 1943 Wallach allowed the American Army to use the main house,[7] and soldiers of the 47th US Infantry enjoyed a large Christmas party in the picture gallery.

On 24 March 1944 the Prime Minister Winston Churchill and U.S. General Dwight D. Eisenhower met at The Grange to discuss the Invasion of Normandy.

However, the furious correspondence in The Times persuaded Baring to pass the house into the voluntary guardianship of the Department of the Environment with a commitment from the Government to pay for restoration to enable public access.