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1st - Arup
With more than 7000 staff worldwide, Arup is rapidly becoming a global force. Turnover at the firm increased 26% last year – rising for the 10th year in a row. Sustainability is one of the firm's core values, and it was closely involved with the World Summit on Sustainable Development in September. One exemplar of these concerns was a sustainable school in northern India that generates its own energy.

Arup had to think quickly when the "wobble" hit the Millennium Bridge in London, but had little trouble in making pedestrians feel more secure. Requests for help over this phenomenon in other parts of the world are now coming in thick and fast. The firm has also played a central role in the engineering assessment and recovery operation at the ground zero site in New York.

'Last year their fees topped £400m, they completed a wonderful case study – a sustainable school in the Himalayas – and successfully put the wobbly bridge behind them'

2nd - Buro Happold
This multidisciplinary consultant sees the world as its market: the firm is working on improving slum infrastructure in Ahmedabad, India, and on a land reclamation project in Kuwait – not to mention projects in Europe, the USA and south-east Asia. Closer to home, it is playing key roles in the BBC's White City development in west London and redesigns of Ascot racecourse and Arsenal football club. Its turnover was up an amazing 48% last year.

'2002 saw them become the first construction firm to gain worldwide Investors in People accreditation. Fees were up nearly 50% and they won nearly 50 major awards'

3rd - Turner & Townsend
This consultant is growing rapidly: group fee income has increased 47% over the past year and by 81% over the past three years. Staff numbers have risen by more than 20% to almost 1000. Turner & Townsend operates from 42 offices throughout the world and has a forecast turnover of £57m for this year. The practice makes a point of listening closely to clients – which seems to be paying off, as 75% of them are now regular customers.

'Fantastic business results … Its case study was the new home for the Greater London Authority, which it managed on behalf of the Government Office for London'

4th - Mott MacDonald
Over the last two years Mott MacDonald has added £170m to its revenue and swelled its ranks of design professionals to 850 internationally. The practice now has operations in 30 US cities and has opened 12 in India. In May 2002 the firm joined forces with Franklin + Andrews to widen its field of expertise and project delivery capabilities. The firm is also pursuing web-based project management, and spent £4.5m on a bespoke system.

5th - WSP Group
Client care has been a central feature of WSP's strategy. It has worked for many years with client BAA and its suppliers, delivering value-added products and services in a non-adversarial partnering environment. Another well-established client is the Royal Mail Group, for whom it manages and operates the Royal Mail's property help desk. It works closely with the contractor Crown House Engineering and believes this kind of alliance is crucial to success.

6th - Cyril Sweett
This one-time quantity surveyor has transformed itself into a multidisciplinary consultant. With contracts in the PFI, healthcare and retail markets, the firm prides itself on the amount of repeat business it obtains, but it is also increasingly winning commissions from eminent first-time clients, such as the Royal Bank of Scotland and IBM. Notable developments include a £1m IT infrastructure and the introduction of an employee share ownership plan.