These policies had a major structural effect on the city's economy. While government policy had limited success in preventing the growth of Birmingham's existing industries, it was much more successful in preventing new industries establishing themselves in the city. Birmingham's economic success over the previous two centuries had been built on its economic diversity and its ongoing ability to adapt and innovate – attracting new businesses and developing new industries with its large supply of skilled labour and dynamic entrepreneurial culture – but this was exactly the process that government industrial location policy sought to prevent. Birmingham's existing industries grew strongly and kept the economy buoyant, but growing local fears that the city's economy was becoming over-specialised were dismissed by central government, even though danger signs were growing by the early 1970s. In 1950 Birmingham's economy could still be described as "more broadly based than that of any city of equivalent size in the world", but by 1973 the West Midlands had an above-average reliance on large firms for employment, and the small firms that remained were increasingly dependent as suppliers and sub-contractors to the few larger firms. The "City of Thousand Trades" had become over-specialised on one industry – the motor trade – much of which by the 1970s had itself consolidated into a single company – British Leyland. Trade union organisation grew and the motor industry in particular saw industrial disputes from the 1950s onwards. A city that for most of its history had a reputation for weak trade unionism and strong cooperation between workers and management, developed a reputation for trade union militancy and industrial conflict.