to the surrounding agricultural land, and good road connections to London in the south meant Cambridge has historically served as an important regional trading post. King Henry I granted Cambridge a monopoly on river trade, privileging this area of the economy of Cambridge. The town market provided for trade in a wide variety of goods and annual trading fairs such as Stourbridge Fair and Midsummer Fair were visited by merchants from across the country. The river was described in an account of 1748 as being "often so full of [merchant boats] that the navigation thereof is stopped for some time". For example, 2000 firkins of butter were brought up the river every Monday from the agricultural lands to the northeast, particularly Norfolk, to be unloaded in the town for road transportation to London. Changing patterns of retail distribution and the advent of the railways led to a decline in Cambridge's importance as a market town. Cambridge today has a diverse economy with strength in sectors such as research and development, software consultancy, high value engineering, creative industries, pharmaceuticals and tourism. Described as one of the "most beautiful cities in the world" by Forbes in 2010, with the view from The Backs being selected as one of the 10 greatest in England by National Trust chair Simon Jenkins. Tourism generates over £750 million for the city's economy. Cambridge and its surrounds are sometimes referred to as Silicon Fen, an allusion to Silicon Valley, because of the density of high-tech businesses and technology incubators that have developed on science parks around the city. Many of these parks and buildings are owned or leased by university colleges, and the companies often have been spun out of the university. Cambridge Science Park, which is the largest commercial R&D centre in Europe, is owned by Trinity College; St John's is the landlord of St John's Innovation Centre. Technology companies include Abcam, CSR, ARM Limited, CamSemi, Jagex and Sinclair. Microsoft has located its Microsoft Research UK offices in West Cambridge, separate from the main Microsoft UK campus in Reading, and also has an office on Station Road. Cambridge was also the home of Pye Ltd, founded in 1898 by W. G. Pye, who worked in the Cavendish Laboratory; it began by supplying the university and later specialised in wireless telegraphy equipment, radios, televisions and also defence equipment. Pye Ltd evolved into several other companies including TETRA