TThe Old Course hotel company lifted its pre-tax profits from £214,000 to £1.4million in 2015, the year in which the Open Championship returned to St Andrews.

Its latest accounts show that Herb Kohler, the American plumbing magnate who owns the Old Course Hotel and Duke’s course, has so far ploughed £35 million into developing adjacent Hamilton Hall into luxury apartments.

Last year’s Open injected some £140m into the Scottish economy, with 93,000 golf fans flocking to St Andrews and £88m spent by visitors to Scotland.

Old Course directors, writing in the report, say the Open helped drive an increase in the underlying trading revenue of the hotel, golf resort and spa, with luxury apartment sales accounting for the balance of the £3.3m rise in revenues to £21.9m.

But they say a 1.2per cent rise in occupancy rates was offset by investment in refurbishment, sales and marketing, and the wage bill. The headcount rose from 383 to 398 during the year.

They also say: “The uncertainty surrounding the UK’s potential exit from the EU will present a risk to the company in 2016.”

The profit cut the company’s accumulated losses from £15.1m to £13.9m.

Development work in progress, however, is shown as still running at £30m, plus a provision of almost £5m for likely shortfall between cost and selling price of the ‘Hamilton Grand’ apartments.

The company spent over £325,000 with its parent Kohler Co on various services last year.

Its outstanding loan to Kohler Mira stands at £57.1m.

Mr Kohler bought the resort in 2004 and in 2009 he added Hamilton Hall, the much-photographed seven-story building next to the Royal & Ancient clubhouse and overlooking golf’s most famous course.

The building opened as a hotel in 1895 but during the Second World War it was used as a training base for the RAF. It later became a hall of residence for St Andrews University.

The first apartments went on sale three years ago at prices from £1.3m.

Owners enjoy a members’ library and grill restaurant, a roof garden, valet parking, a 24-hour concierge and a bar open to the public.

Mr Kohler’s corporation also owns the Whistling Straits links which will host the 2020 Ryder Cup in its home state of Wisconsin.