Nestling on the banks of the Thames, between Marlow and Henley is SAS UK. The site combines the best of all worlds: state-of-the-art offices and an impressive mansion, as well as beautiful grounds.

Wittington House is just over a century old, although archaeological remains on the estate date from the Iron Age. The site was acquired from Oxford University, and the estate built in 1898 as a family home for Hudson Ewbanke Kearley, later Viscount Devonport. Kearley's fortune was based on importing and distributing tea - remembered by the sprig of tea in the carved crest over the main door. He also owned International Stores (Kearley and Tongue), was the Member of Parliament for Devonport, Minister of Food during World War I, and Chairman of the Port of London Authority.

The house was designed and built by Reginald Blomfield, later knighted, who was also responsible for the restoration of Chequers, the British prime minister's country residence. His original design for the house was never completed to Kearley's satisfaction, and in 1908 he was brought back to replace and enlarge the two wings and completely redesign the frontage.

Other buildings that echo the design include a summer house in the woods to the east of the house, the boathouse down by the Thames, the lodge at the gates, and a 'miniature' of Wittington itself, known as Kingfisher Lodge. This building, now in private ownership, is situated by the Thames below Danesfield House, next door to Wittington, and is beyond the existing western border of the estate. It has its own bridge over the stream and is complete with typical Blomfield details

The Wittington Estate includes the riverside strip below the cliffs - bought by Kearley to annoy his next-door neighbour, Robert Hudson of Sunlight Soap fame, who had acquired the Danesfield estate in the 1890s. This effectively denied Hudson access to the river - a situation that still exists today. Kearley and Hudson had both previously lived in Medmenham, a mile to the west of Wittington, and this is where their rivalry started. Hudson was responsible for building the current Danesfield House, which is the second time the house has been rebuilt.

Wittington is located on one of only two sets of chalk cliffs on the Thames - the other being Cliveden, the former home of Lady Astor and the centre of the Profumo scandal in 1963. Wittington's chalk cliffs have been quarried for generations. Chalk rock from the site was used extensively for building in Hurley on the other side of the Thames, including the tithe-barn and dovecot. Medmenham Abbey's thirteenth century building material was also quarried here, and popular myth maintains that it was also used in early sections of Windsor Castle

Some of the original features of the house were antiques bought in to furbish it either when it was built, or when occupied by Garfield Weston in 1935. The magnificent chimneypiece in the old dining room came from Battersea Rise House when it was demolished for building improvements. Battersea Rise House is reputed to have welcomed nearly every Cabinet Minister from the latter part of the eighteenth century until the middle of the nineteenth century. It was also the home of many well-known people, including William Wilberforce, the MP who led the campaign to abolish the slave trade.

Kearley cared much for the local environment and succeeded in acquiring most of the land visible from the house. Although Blomfield landscaped the estate, Kearley was responsible for actually designing and planting the under-cliff and rock gardens.

Kearley spent 35 years working on the gardens at Wittington. Major effort went into the terraces below the house with hundreds of men being employed for stone picking, and later for the manual movement of earth. This provided major employment for the local community at a time of serious unemployment after the Boer War. The fame of the gardens at Wittington spread, and in May 1931, when the flowering cherries were a mass of bloom, and the rock garden, which by then had become one of the finest in England, was looking its best, Queen Mary visited the site. The gardens were also featured in Country Life magazine in 1927 and again in 1928.

Kearley always regarded the rock garden as his finest achievement. To build it he imported large quantities of stone from Derbyshire. It is still possible to detect echoes of the rockery and water-side gardens that provided the inspiration for many of his parliamentary speeches whilst he was an MP and Minister of the Crown.

There was also an arboretum of rare trees to the east of the house, most of which survived the big storms of 1987 and 1990.

The Thames at SAS UK also features a flash-lock capstan, said to be the only one left in the whole of England. Restored in 1999, it was originally used to pull river barges up the flash-lock prior (and for some time after) the pound lock was built in 1780. Kearley restored and repaired it from time to time from estate oak. SAS UK now maintains this historic site.

After Kearley's death in 1932, the estate was split up and, amongst others, the area around Hurley, originally bought to protect the view, was sold off. Sadly, a caravan park, thus confirming Kearley's worst fears, now occupies much of this land.

SAS is only the fourth occupant of the mansion. In 1935, Garfield Weston, the Canadian owner of Associated British Foods, took up residence. It is believed that the elaborate panelling in the library and study was installed during his sojourn. His coat of arms hangs in the library above the door, together with some unusual carvings representing Hitler and George Bernard Shaw.

In 1948 the Salvation Army took over the house as an Eventide House for elderly ladies at a peppercorn rent from the Weston family. The estate was disbanded after Weston's death and sold to Crest Estates in 1985 for renovation and conversion to offices. In November 1985, SAS bought the house as its UK headquarters.

SAS' estate manager, Dave Clark, first came to work at Wittington in the Salvation Army days in 1971, when the back lawns were cut by hand with a scythe. As well as the daily maintenance of the grounds, he oversees the restoration of the grounds - a long-term project, which includes the renovation and replanting of the herbaceous borders, rhododendron beds, lawns, the front paddock and 18-acre meadow, tree-planting to fill the gaps on the drive and the restoration of the old Rose Garden, which had disappeared after many years of neglect.

After moving into Wittington with only 11 people, SAS grew so fast that it was soon realised that, amongst other things, new training facilities for customers would need to be added. A new reception area, training facility and offices were built inside the existing walled garden in 1993. The scheme was sensitively designed to make the building virtually invisible from outside the garden wall, and includes terraces and water cascades. SAS was awarded the prestigious Malcolm Dean Design Award for its sensitive approach to developing the property.

To accommodate the needs of its growing staff, the old stables were transformed into a restaurant, which was opened in November 1995. This marked the end of building on the existing Wittington site.

In 1996, SAS bought 34 acres of land adjacent to the estate from the Ministry of Defence, bringing the total size of the Estate up to 110 acres. The first stage in developing the site was completed in 2002 and the new building consists of a hub and one wing (the second wing will be built as part of the second stage). The hub includes a reception area, an atrium, meeting rooms, and a restaurant. The current wing seats 240 people in an open plan environment. The building confirms SAS' commitment to the environment - it has been designed as low energy, has high levels of insulation and glazing and is naturally ventilated rather than air-conditioned. SAS will also be restoring the cricket pitch which was originally located on the site, for use by the local village.