Stephen James Group has come a long way since Duncan Collins launched his first business modestly, but colourfully, in the early 1970s.

It was a used car showroom with a small workshop and five employees. There was an early cashflow problem.

Three weeks after opening all six cars in the showroom had been sold.

Delays in payments from finance companies meant he would have to wait 10 days before he could buy more stock.

His financial saviour was Bernie, a horse trader turned car salesman he first met in a previous job.

By chance Bernie walked in, wearing his customary boots and baggy grey trousers held up by wide maroon braces.

When he heard about the financial hitch he handed over £5,000 in notes as an interest free loan for a year or two.

Soon afterwards Duncan Collins bought larger used car showrooms in Colney Hatch Lane between Islington and Muswell Hill in north London.

The business was called Stephen James after the previous owner’s two sons, and he kept the name.

In 1985 Collins acquired the BMW franchise for nearby Enfield, which opened with 27 employees at a showroom in London Road near the town centre.

The growth of Stephen James Group began in 2003 with the acquisition of a large property on Enfield’s Martinbridge trading estate alongside the dual carriageway A10.

This was the location for its new Enfield dealership and a centre to handle all preparation work for the group’s four dealerships.

The recession brought a change of plan. PDIs were moved back to dealership workshops and the space was used to open a self-storage centre.

In 2004 Stephen James opened its showroom overlooking the A10, a busy route in and out of London, with Mini on the ground floor, BMW upstairs and cars on the roof floodlit at night.

A year later the group won the BMW UK dealer of the year award, mainly for innovative features at Enfield.

Mini is the focus of its latest investment.

The company has bought 1.5 acres adjoining its Enfield site to build a separate Mini showroom (a BMW Group franchise condition).

It will also create space for 100 used cars on view to people driving down the A10.

Ben Collins, who leads this development of Stephen James, graduated from Cambridge University with a theology degree.

After a spell in the City he was working for the firm as Mini brand manager when the reborn brand was launched by BMW Group.

Then came some time in the group’s BMW used car department, work as its BMW general service manager and as a dealer principal. He was ready to become MD in 2006, aged 29.

The key date in Collins’ mind is July 26, 2006: “That’s when we became a group”. Turnover leapt from £60m to £150m with the purchase from Whitehouse Group of three BMW and two Mini dealerships, all freehold.

The deal, funded by BMW Financial Services and NatWest Bank for an undisclosed sum, was clinched a year after the death of Brian Whitehouse, chairman and major shareholder of a family business.

It gave Stephen James a BMW outlet at Blackheath (Mini was added later) and BMW/Mini at Bromley (both in south-east London) and Ruxley Corner, near Sidcup, north Kent.