The interventionist stance of the agency led to Wales achieving 20 per cent of the UK's inward investment, with only 5 per cent of the population. Despite the mine closures, it has a below-average unemployment rate.
To promote the Welsh economy, the WDA has reclaimed 30,000 acres of derelict land over the past 10 years, and pounds 1.7bn has been spent on new trunk roads and motorways.
Now the agency is extending its interventionist policies to assist local enterprise. David Farnsworth, the WDA's executive director, says that after attracting 'blue-chip, energetic companies in the electrical engineering sector', such as Bosch, Toyota and Ford, there is a strong market for the supply of high-quality products, which can be met by local entrepreneurs.
'We have to help them supply to make Wales' economic growth sustainable. We want to get supplier chains going.'
This is being achieved partly through an active role in creating joint ventures between large companies, smaller potential suppliers and various parts of the public sector.
The agency is also assisting local companies by promoting links between Wales and other regions in Europe, and organising trade missions and fairs.
Although the WDA refuses to talk of economic planning, it does talk of economic management and managing each town or city in Wales as if it were an enterprise, tackling its commercial weaknesses and establishing its 'niche position'. This involves a new programme, covering 32 urban areas, on which pounds 30m will be spent this year.
Mr Farnsworth said: 'It seemed to us that there were important things we had to do something about.
'Councils that were managing towns never really had a view of their job as managing a business, looking for markets,' he added. 'It was more about deprivation: 'We're in a mess, so let's put money in.' If we want regeneration, it's not a matter of simply feeling sorry about things; we want Wales to perform better.'
The WDA denies that support for local businesses reflects an expected downturn in inward investment, but Mr Farnsworth does admit that Japanese investment in the region will not continue as before - a result, he says, of Japan's weakened economic position. The agency is instead looking for increased investment from the United States, Germany and France.