This summer, Houghton Hall looks different. Its familiar and superbly preserved interiors have been transformed by the return of a collection of paintings removed from the house more than two centuries ago. For a brief period, visitors can glimpse the principal apartments in much the form that they appeared in during the mid 1740s. The effect is nothing short of a revelation.

The creative genius behind the sumptuous apartments at Houghton Hall was William Kent who, in the interior decoration he carried out for Sir Robert Walpole in about 1725-35, brought to Norfolk the spirit of the magnificent Renaissance and Baroque palazzi he had seen in Rome. Kent had spent 10 years in Italy from 1709. He received instruction in painting by Giuseppe Chiari and possibly Bene-detto Luti, both disciples of Carlo Maratta. The master of Late Baroque Classicism, Maratta was then regarded as the greatest living artist in Rome.

Walpole himself had never been to Italy, nor had the Palladian Revival architect Colen Campbell, from whose designs Houghton was built in 1722-28 (although much of the house, and certainly its four Baroque domes, was the idea of the architect, James Gibbs who had lived from 1703 to 1709 in Rome). Without Continental experience to draw on, Campbell found interior decoration a problem. This is clearly shown, for example, in the dull, panel-led rooms he designed for the enormous Wanstead House, Essex, as illustrated in the first volume of Vitruvius Britannicus (1715).

Kent blew this world apart when he arrived like a whirlwind at Houghton, injecting Italian warmth, colour and spendour throughout the principal interiors. He aimed to treat the interior as a totality, designing door-cases, ceiling paintings, plasterwork and cornices, pier tables and pier glasses, seat furniture, upholstery and elaborate picture frames. Nothing like this had been seen before in England, where he was the first architect and decorator to design furniture for settings that he had himself created. His opulent, gilded mahogany furniture at Houghton was massive and architectural in conception, swirling with Genoese Baroque ornament, which included his favourite scallop shells.

The detailing of furnishings and architecture was all related and, where possible, to the iconography of Wal-pole’s remarkable collection of paintings as well. This comprised more than 400 works of art, many in the dazzling Baroque manner, by the greatest Italian, French, Dutch, Spanish, and English masters. Among the paintings were 13 works by Maratta that were hung in the principal drawing room at Houghton-the Carlo Maratta Room-along with four paintings by Kent’s master, Giuseppe Chiari. Considering the chauvinist Protestant temper of Augustan Eng-land, the collection was surprisingly rich in Catholic devotional imagery.

The furniture and interiors designed by Kent at Houghton are remarkably well preserved, but nearly all the paintings have long disappeared. In 1779, Walpole’s grandson sold 204 paintings from the outstanding collection in the house to Catherine the Great. To compound this loss, she did not choose to retain the carved and gilded frames that Kent had designed for them. These are now lost, although some original frames do survive at the house.

The present exhibition-proposed as recently as three years ago by the curator Dr Thierry Morel and enthusiastically adopted by Lord Cholmondeley-has brought some of these lost pictures back to Houghton after more than 200 years’ absence. Some 70 paintings from the Hermitage, Pavlovsk, Tsarskoye Selo, and other collections in Russia and elsewhere, have now been arranged in positions that, as we know from contemporary plans were chosen by Kent, Sir Robert Walpole, and his son, Horace.

To be precise, the arrangement reflects the hang of paintings following Walpole’s fall from power in 1742, at which time, many new paintings were brought to Houghton from his London house in Downing Street. The exhibition is accompanied by a full catalogue and visitors are provided with well designed booklet guides that describe the rooms and identify the paintings within them.

We can now appreciate for the first time the remarkable match between the paintings, their position on the walls in symmetrical patterns, the architectural articulation of the walls and ceilings, and the design of the furniture. The tour of the interior begins in the Stone Hall, a room essentially unaffected by the exhibition. Visitors would originally have walked from this into the Saloon (although this is the culminating interior of the tour today).

The Saloon was the principal room of state and it preserves 18th-century upholstery and wall hangings of the same material. Over Kent’s Ionic pedimented chimneypiece hangs once more Salvator Rosa’s Prodigal Son (1651-5), one of Walpole’s most treasured pictures.

In the chimneypiece of black marble, flecked with gold, Kent also introduced a striking contrast by adopting white Carrara marble for features such as the capitals and frieze of its pairs of Ionic columns. The echoing rhythms of these, breaking forwards and backwards, might be paralleled in the music of Bach, born, like Kent, in 1685. Kent used the same black-and-gold marble for the tops of his side tables in this room.

The Saloon establishes certain visual themes that are echoed in the rooms beyond. The first of these, the White Drawing Room, or Carlo Maratta Room, possesses a chimneypiece of white marble with decorations in black marble. This scheme reverses the treatment of the Saloon chimneypiece of black marble decorated in white. And the fire-place of the Green Velvet Bedroom beyond wittily returns to the black marble with white decorations of the Saloon.

As originally completed, the Carlo Maratta Room was hung with green velvet, but this was replaced with white-silk wall hangings after 1779. One of the most inspired decisions made for the current display was to cover the white silk temporarily with green velvet. Its dark tone brings out the bright colours of the Baroque paintings, such as Maratta’s commanding portrait of Clement IX. In a red-velvet cape termed a mozzetta and his papal cap or camauro, he sits on a chair upholstered in a similar material, so he neatly continues the colour scheme of the adjacent Saloon.

Each room in the sequence offers new surprises. Preserved in the Cabinet Room is the elaborate carved and gilded frame designed by Kent for the tall and narrow portrait by Rubens of his second wife, Hélène Fourment. Now converted into a mirror, it is a good representative example of Kent’s lost frames. The painting it enclosed was too fragile to travel from Lisbon, but it is hoped to insert a copy of it into the frame.

The Embroidered Bed-chamber, with Kent’s ceiling painting of the sleeping Endymion, is once more home to Poussin’s Holy Family with SS Elizabeth and John the Baptist (1655), for which Walpole paid the highest price then given for a Poussin (he owned eight). The cherubs that Kent included in his sumptuous frame for this painting echo the curly-headed Christ Child and Baptist.

In the Tapestry Dressing Room, Mortlake tapestries of the Stuart dynasty, of 1672, possess borders decorated with leaf motifs and cherubs bearing fruit garlands. Kent echoed these features in his carved friezes and ceiling painting of Flora, goddess of flowers.

The considerable height of the tapestries was reflected in the strikingly vertical painting by Jean Lemaire, called Lemaire-Poussin, Consulting the Sibylline Oracles (about 1635), showing the Sibylline books being brought out from the Temple of Jupiter. Although comparatively little known, it is one of the most striking of all architectural capricci, its partly imaginary ancient Roman buildings including a slender skyscraper, apparently inspired by the now demolished Septizonium in Rome.

The main dining room is known as the Marble Parlour because the whole of the west wall with its arched screen and buffet alcoves is of variegated marble. This arrangement originated with James Gibbs, although its final form was worked out between 1728 and 1732 by Kent. The focus of the room is a chimneypiece with a Rys-brack panel of The Sacrifice to Bacchus. A magnificent preparatory drawing for this sculpture on loan from the British Museum is currently on display in the house. Echoing this Bacchanalian theme Kent included bunches of grapes in the chimney-piece, the painted ceiling and its cornice, the sconces, the mirror and pier table between the windows and even the architraves of the doorcases.

The original hang of the dining room has been dramatically restored. It includes two, full-length portraits by Van Dyck, the Earl of Danby in Garter Robes and Sir Thomas Wharton and two still-life paintings of grapes and melons by Michele Pace del Campidoglio, the popular Roman painter who specialised in fruit and flowers.

The Common Parlour contains powerful, even astringent, male faces, all returned home from the Hermi-tage: Inigo Jones and Sir Thomas Chaloner by Van Dyck, and Kneller’s cadaverous John Locke and powerful Grinling Gibbons, strangely clutching a cast of Bernini’s marble head of Proserpine in his left hand. We can now understand how this hugely imposing portrait relates to the almost over-powering grandeur of Kent’s carved marble chimneypiece below it, layered with white and purple-and-white marble from Seravezza near Carrara.

Given Kent’s brilliant work at Houghton, it is ironic that the waspish Horace Walpole should have condemned his reputation, cruelly attacking Kent, concentrating unfairly on his inadequacies as a painter. Kent’s reputation did not begin to revive from this malice before the early 20th century, but the current unforgettable display at Houghton has reinstated him as one of the greatest creators of beautifully co-ordinated interiors in the history of English architecture.

For details of the exhibition, which runs until September 29, visit www.houghtonhall.com or telephone 01485 528569

Compare photographs of the house then and now at www.countrylife.co.uk/houghton