the 1890s (growing after World War I), by which time industries such as shipbuilding, textiles and steel were already established. In the inter-War years modern industries emerged, with aerospace forming clusters around London, Bristol and in Hertfordshire. The Hertfordshire cluster no longer exists. The early electronics industry generally preferred the south, especially the home counties. Today there is no heavy manufacturing industry in which UK-based firms can be considered world leaders and no product in which a UK city or region is the world leader. However, the Midlands, in particular, remains a strong manufacturing centre, with around a fifth of employment dependent on manufacturing, and the East Midlands Development Agency has a policy to maintaining this characteristic. More recently, high technology firms have concentrated largely along the M4 motorway, partly because of access to London Heathrow Airport, but also because of the economies of agglomeration. However, the general pattern remains that the south has lower, and falling, reliance on manufacturing. Finance and services Once, every great city had a stock exchange. Now, the UK financial industry is concentrated overwhelmingly in the City of London and Canary Wharf, with back office and administrative operation often dispersed around the south of England. London is one of the world's great financial centres, which is one of the factors that is commonly considered to make it a world city. Central London contains some of the most expensive commercial property in the world because of this. From around the early 1990s London has been able to boast of having more U.S. banks than New York, as well as being host to branches of more than five hundred overseas banks. It is the principal financial centre of the world, ranked alongside New York and Tokyo as one of three where any serious financial player must be represented. The City of London has around 300,000 employees, largely concentrated in the financial and professional sectors. Within London, the desire for banks to be there put pressure on the City of London's ability to accommodate them. In the mid-1980s a crisis point was reached and, although the city was able to expand its stock of modern office space, this did not happen before Canary Wharf had been set up as a competitor. The irony is that Canary Wharf was built in the London Docklands that had, until 1970, been among the largest docks in the world. All manner of