Historically, the English county of Berkshire has been bordered to the north by the ancient boundary of the River Thames. However, much of the border with Oxfordshire in the western part of the county was moved in 1974. Alfred the Great was born in Wantage, historically in Berkshire, but now in Oxfordshire for administrative purposes. The Great Western Railway reached Didcot in 1839. MG (part of Morris Motors) was founded in Abingdon in 1929. The Vale of White Horse and parts of Oxfordshire south of the Thames were previously part of Berkshire, but were lost to the county in 1974. Conversely, the Slough area north of the Thames is historically part of Buckinghamshire, but became ceremonially part of Berkshire in 1974. Important historical abbeys include Abingdon Abbey and Reading Abbey. Oscar Wilde was imprisoned in Reading Gaol after his court case. The county is known as the Royal County of Berkshire since the Royal residence of Windsor Castle is within it. Politically, the county is now made up of unitary authorities. Location and administration During the heptarchy, the area formed part of the kingdom of Wessex, and relics of Saxon occupation have been discovered in various parts of the county. Of these the most remarkable are the burial grounds at Long Wittenham and Frilford, and there is evidence that the Lambourn valley was occupied in early Saxon times. The cinerary urns found in Berkshire undoubtedly contain the ashes of the Anglians who came south under Penda in the 7th century. The fortification called Cherbury Castle, not far from Denchworth, is said to have been first made up by King Canute. At the time of the Norman Conquest, Berkshire formed part of the Earldom of Harold, and supported him staunchly at the battle of Hastings. This loyalty was punished by very sweeping confiscations, and at the time of the Domesday survey no estates of any importance were in the hands of Englishmen. When Alfred the Great divided the country into shires, this county received the name of Berrocscir, as Asser says, "from the wood of Berroc, where the box-tree grows most plentifully". At the time of the survey it comprised twenty-two hundreds; in 1911 there were only twenty, of which eleven retained their ancient names. Many parishes have been transferred from one hundred to another, but the boundary of the county is practically unchanged. Part of the parishes of Shilton and