Andrew Mackintosh describes himself as PR manager at wholesaler Suma, but that's probably because it is a Wednesday. Speak to him on a Tuesday and he's a business consultant. Catch him later in the week and he's sales manager. Mackintosh, like most of Suma's 150 employees, has at least three different job titles thanks to its rather unusual business approach.

Suma is a workers' co-op. Day-to-day operations are carried out by self-managing teams of employees, all of whom have an equal stake in the business, are responsible for multiple job functions and are paid the same hourly wage. There's no chief executive, no MD and no chairman. Nevertheless, it is a business model that works. Over the past 33 years Suma has steadily grown from a small wholefood trader selling "lentils to hippies" into a £25m business that supplies to 4,000 customers including Waitrose, Sainsbury's, Booths and independent whole food shops across the UK.

It also supplies the prison service and education sector and has conducted research with the Soil Association on the organic food market. Turnover is forecast to reach £30m by the end of 2010. Suma claims to be the biggest single-pay organisation in ­Europe and accounts for 25% of UK worker co-op turnover. The reason for the business's success, says Mackintosh, is its culture of fairness. "If you are paying someone three times less than someone else the desire is not there to work as hard," he says. "Everybody has an equal voice and an equal stake in the business and they appreciate this."

This doesn't mean every single decision the company makes is put to workforce vote. Decisions are made by the management committee, a team of six appointed to make the business plan work. This team then speaks to the different areas of the business - transport and warehousing, finance, sales, buying and services. The company also holds quarterly board meetings where staff can raise any points. "We are not herding cattle," says Mackintosh. "We work like ripples in a pond. At the centre is the management committee and the second circle is the functional area."

It is Suma's approach to multiskilling that makes its model so successful. All workers are trained in a number of functions, making it flexible and fleet of foot. "We optimise efficiencies by bringing people from all areas to help where necessary," says Mackintosh.

All new staff have to work for six months in the warehouse, picking orders and driving trucks. "People understand how exhausting it is, so when people are asked to do an extra three-hour shift packing pallets everyone knows exactly what it entails."

In the second six months workers undertake a more paper-based role. "We take accountants and turn them into drivers and take drivers and make them credit controllers," says Mackintosh. "Every single staff member can read a balance sheet. We have the quickest graduate training scheme in the country, with people going from shopfloor to boardroom in 18 months."

The Suma model means it is not short of fans; every advertised position gets 200 to 400 applications. Yet Mackintosh is keen to stress Suma is a business not a charity, and must work hard on driving the business forward. The warehouse has six-week stock turnover but the company wants to reduce this to five in three years. It currently holds 10% of its turnover as stock but Mackintosh says it is working to a more just-in-time approach. It won't be easy, he admits. "We still don't have the buying power for chilled products so have to buy things in bulk when we are offered it," he says.

The company also plans to boost its own label side of the business. As well as supplying thousands of well-known brands - from Tyrrells and Fentimans to Green & Black's and Nairns - Suma also has its own brand of products, including nuts and seeds, oils and vinegars, tinned vegetables and spreads.

The brand is worth £6.5m but Suma wants to grow this to £9m in the next three years by expanding further into fine foods. "We will continue to push ourselves," says Mackintosh. "We wouldn't have lasted more than 30 years if we had put ethics to the fore at the expense of the business." n