Williams does all the things you would hope - picking up on cornice lines, using bits of old wall, bringing together existing buildings with a new education suite around a courtyard, separating old from new by means of glazed slots, sinking new parts such as a café into the rising ground, selecting the right pale stone, even forming a timber-lined underground link between the new visitor and education rooms and the house. It is done with assurance, but it is also done with character. There is as much of a personality in the new work as there is in the old. This is not least because - since the rooms at Compton Verney were pretty much derelict above the ground floor as found - the new galleries on the upper levels are essentially just that. New galleries, not awkwardly-converted rooms. English Heritage was closely involved.

There is, for instance, a fine new staircase - not a whiff of historicism - flanking the portico, with a beautifully modelled new arched doorway into it. The folk and popular art galleries right up under the roofs, with their old shop signs and naïve paintings, are suitably domestic in scale and will be a hit with children. The lower floors have different characters, the ground-floor rooms - where the Italian and German art is displayed - being logically the grandest and most original. Throughout, Williams (working with conservation architects Rodney Melville and Partners) has carefully preserved your sense of orientation, so that selected views out remind you where you are in the house. He has developed a system of full-height horizontal sliding shutters on the first floor to allow curators as much or as little daylight and outward vision as they want. So much for architects: for his six-month show, Greenaway appears to have ignored this sophisticated system in favour of cruder blackouts. Williams looks pained, but tactfully refrains from passing judgment.