The rest, accounting for more than 70 per cent of the college budget, are spread across the length and breadth of the land, trained through a network of deals with companies from supermarket giant Tesco to the cleaners at Heathrow Airport.
Halton is one of Britain's biggest franchisers, and typifies the sort of work currently under detailed scrutiny by government ministers in the wake of the crisis over college expansion.
That work - training in the workplace, backed by government subsidy - has been approved in principle by a government-a ppointed working group on franchising. Ministers and Opposition leaders have emphasised partnership between colleges and the private sector.
But the franchising working group, whose full report will be completed in the summer, has raised profound questions about the way quality is maintained on courses run outside colleges, and about whether public money is simply replacing the sort of training employers would, and should, carry out anyway.
Halton's principal, Martin Jenkins, is a vociferous defender of the type of workplace training which has produced more than 200 per cent growth since the college became self-governing in 1993.
The college, in Widnes, Cheshire, now works with 220 organisations, many of them well-known national companies, and has developed an entrepreneurial marketing strategy, which openly regards the whole of Britain as its catchment area.
Mr Jenkins regards his franchised work as a kind of private finance initiative, arguing that the college uses employers' premises, equipment and even staff, adds support and training, and delivers progress towards national training targets.
But he is adamant that the quality of work is high, and that his college's training offers clear added value for staff and employers alike.
"We recognised the need for this work a long time ago," he said. "We have very well-developed mechanisms for quality, and policies which ensure that value is added in the workplace.
"We even have an audit of companies before our work starts. Unless they show a commitment to training or have an action plan for dealing with the issues we are not happy with, we do not work with them."
And he insists the college does not bid for training on price. Some early franchises are still subsidised directly by the college, but most are funded largely by companies, with public money simply paying for staff support from the college.
"Some organisations have asked us to move into Dutch auctions," Mr Jenkins said. "But we do not tender on price; we only bid on quality, and a lot of our companies pay us. People will come to understand that distance is no longer going to be an obstacle to training. I think workplace training probably adds more value, because it's a hybrid system."
He accepts that franchising may have to be funded on a special rate, lower than that for traditional college courses, but says a fixed formula for public, employer and employee contributions to training would not reflect the real world.
Demand for expertise from colleges has certainly been high. Halton staff say the demand from companies has been enormous, with word-of-mouth recommendations bringing much of the college's huge growth. New franchises are constantly being developed, despite recent concerns about funding.
The college's private sector partners are keen to trumpet the success of their work with the college. but they are equally adamant that it has been the pump-priming effect of state support for the college's efforts in the workplace that persuaded them to invest in NVQ and other nationally-recognised qualifications - and has helped them to extend training programmes.
There is a consensus among Halton's partners that the ability of the college to offer support has allowed them to embark on training they would otherwise not have attempted.
"We needed the help in the first place when we were trying to sell NVQs, " said Lynne Kirby, training centre manager for Securicor Omega Express. "With the college behind the training, it had a bit more impetus. Without it we would not have got it through the company. Now we are beginning to see the success of it."
Glennis Jones, of Scope, formerly the Spastics Society, added: "As a charity we do not have an awful lot of money, although we do put a lot of money into training. What this has done is to enable us to focus on quality training."
Danny Rodman, of train-makers Bombardier Prorail, said his company's restructuring programme was built on re-training provided by the college. "Bringing in an external third party has a lot of oomph," he said.