Osterley Park is a country house in the west of London. It was built in the 1560s for Sir Thomas Gresham, founder of the Royal Exchange, and transformed by Robert Adam in the 1760s. Externally this makes it rather a hodgepodge of styles, but internally it is a superbly tasteful collection of the best of the Georgian style. It now belongs to the National Trust.

The original design was a square building of red brick with towers at each corner, in the manner reminiscent of fortification then current. The Elizabethan proportions are preserved in the nearby stable block, a handsome building of three sides now serving as shop and tea rooms, whereas Adam's improvements give the house a classical portico and wide steps on two sides, in the then fashionable grey stone, and expand the windows to Georgian sizes, which was no doubt better for the family living there but makes it look unbalanced, sitting oddly between the two dates.

Inside, however, it is all Adam, and all exactly right. By this time it had passed to the Child family, proprietors of Child's Bank (much later to be absorbed by the Royal Bank of Scotland). They were rich and wanted to make an impression, but they had good taste. Compared to some houses, there is no gaudiness, no excess. There is gold where it is needed to add lustre, there is opulence in the furnishing of the largest gallery, and there is richness and power in the overall effect, but it is on a very human scale, and very livable. The private rooms are beautiful, elegant, and subdued. Even the one with carmine walls: it is a pleasantly muted Georgian carmine. The proportions of the rooms are perfect, whether large or small, and the pictures on the walls are, if not masterpieces, always worth looking at.

One of the Child heiresses eloped to Gretna Green later that century, and the paterfamilias, though eventually forgiving her, ensured that Osterley passed not to her or her wastrel husband but to a younger of the children, and so in time (when she was eight, in 1793) the estate came to Sally, later to be Lady Jersey, "Queen Sarah", one of the great society hostesses of Regency London. She and Countess Lieven, wife of the Russian ambassador, could make or break an aspiring lady in good society, as her friend Beau Brummell could for a gentleman.

It was still in the Jersey family when it was given to the nation in 1949. The National Trust have bought up all the land around, part of the original patrimony, to ensure it is kept perpetually farmland and never encroached upon. Though, alas, on the north boundary is the terrible M4 motorway and from the south-west come incessant invasions of low-flying Jumbo jets from Heathrow, neither of which even the National Trust can prevent. Nearest Tube: Osterley, on the Piccadilly Line.

There are grounds with trees and long lakes, perfectly adequate for their kind, but the beauty is in the interior. The Victoria and Albert Museum ran it for the Trust for many years, but since 1996 the Trust themselves have started throwing out historically inaccurate changes the V&A made and getting it back to its correct appearance at the height of the Childs' possession.