A historic county in the South of England. It is also often referred to as the Royal County of Berkshire because of the presence of the royal residence of Windsor Castle in the county; this usage, which dates to the 19th century at least, was recognised by the Queen in 1957, and letters patent issued confirming this in 1974. Berkshire borders the counties of Oxfordshire, Buckinghamshire, Surrey, Wiltshire and Hampshire, and is usually regarded as one of the home counties. Under boundary changes in 1995, it also acquired a boundary with Greater London.