The 18th-century remodelling of the house and grounds was the work of style guru and architect Robert Adam and the Child Family who employed him.

Robert Adam's job was to give a crumbling Elizabethan house with a host of vogueish additions a clear architectural vision. Bringing to an end piecemeal repairs and additions of varying quality and style was the challenge in 1761. What he created became one of the most magical homes in the British Isles.

Self-confident, brusque and with an unrivalled command of classical antiquity, Robert Adam was London's architectural style leader. Osterley displays the full range of his transformations and his own development from early boldness to mature fluency.

Charged with modernising the house and reducing its size, much of his proposal was too drastic for Francis Child. It was Robert Child who oversaw the addition of the 'transparent' portico, a neo-classical design with echoes of the Portico Septimus Severus in Rome and Pliny's Tuscan Villa.

The footing for the new front was made in 1764, with the steps retained and the courtyard raised to the same level. Visitors noted that the work was still not quite finished in 1772, although 'several fine rooms' were. The Drawing Room and Eating Room were probably completed first in at least two stages, starting with the ceilings. They were not as refined as later rooms.

The principal staircase was also made in two stages. The Library, however, was made in its entirety in 1766. Work on the Hall was delayed until 1767-8 to allow the formation of the new entrance front.

Robert Child became hooked on improvements. In 1772 he commissioned a state apartment (despite the fact that they were considered very outmoded) to include the Tapestry Room, velvet State Bedroom and painted Etruscan Dressing Room. These three rooms were conceived as a sequence of different styles and colours, indicating the elements fire, earth and water.