It is a familiar misconception that as workers slip out, and the night draws in, a director reaches for his desk drawer and pulls out a bottle of a whisky.

In that case, staff at Denne Joinery could have been forgiven for worrying about their boss Nick Kingsman.

Bottles of dark spirit were popping up all over his office at the firm’s workshop in Bramling, near Canterbury, where it has created doors and frames for the Duke and Duchess of Cambridge’s residence at Kensington Palace and the 1 Hyde Park development, where flats sell for more than £100 million.

The tipple, however, was not scotch but Grenadian rum and, fortunately, the cause was not alleviating any work-related stress – or not entirely.

Instead, serial entrepreneur Mr Kingsman was embarking on a new business venture which has taken him from the shores of the Caribbean to the starting line of sailing regattas in Lanzarote and the Isle of Wight.

The voyage has been charted thanks to an instinctive punt taken while holidaying in Grenada, where he owns a villa.

Three years ago Mr Kingsman got to know the bosses of Westerhall Estate, a family-owned rum distillery on the island operating since the early 18th century.

Having fallen in love with the spicy liquor and discovering it did not have a British presence, he inquired about becoming its first UK importer and distributor.

This year, the side project will hit the big time when Westerhall Estate sponsors the prestigious Cowes Week Regatta this summer.

“The rum was really fantastic so I thought ‘let’s give it a whirl’,” said Mr Kingsman, sitting next to daughter and colleague Annabel, 26, who helps him run the business with brand manager Liberty Hanson.

“It has really taken off. I initially brought back 50 cases and thought if worst comes to worst, we would drink them if it didn’t sell. But it proved to be a real winner.”

Trendy bars in Canterbury and London are stocking Westerhall Rum after Mr Kingsman and his team made the Caribbean drink shipshape for the UK market.

His initial difficulty was that each rum had a different name and bottle size, making it tough to establish the brand.

He brought in creative marketing agency The Wow Factory, based in Charing, who standardised the bottles and designed a new consistent identity.

“We needed it uniform and with corporate branding,” he said. “Some bottles were tall, some were short, with different labels and it looked a mess.

“At the beginning it was difficult to get bars interested in it because of the way it looked. We knew it would do well if we could get the look of it better.”

The growth of Westerhall has undoubtedly been helped by the growing demand for niche products in the drinks market, according to Mr Kingsman, 62, who lives in Ickham.

“The move to smaller, different brands in bars has been a big trend and we got in there as one of the earlier ones.

"I initially brought back 50 cases and thought if worst comes to worst, we would drink them if it didn’t sell..." - Nick Kingsman, Westerhall Rums

"We have lots of inquiries from restaurants wanting to be able to use our rum in their cocktails. Bars want to have that bottle on their shelf because it looks good. Otherwise the brands merge into one. We really stand out.”

Daughter Annabel added: “To see the whole country’s tastes change towards something new and different, which you can have an impact on, is cool.”

Yet why go to the effort of running another business when you are already running two successful companies?

Alongside Denne, which was founded in 1803, Mr Kingsman runs the UK arm of Italian vineyard technology distributor Valente.

“With Westerhall, it’s mixing business with pleasure,” he said. “It’s a fun business. Construction can be pretty boring but the opportunity and potential of the rum business is good fun. It’s a bit like motor racing. It has a prestige to it.”

Denne Joinery started life when carpenter George Henry Denne bought a barrow in 1803, launching GH Denne.

Originally based in Deal, it evolved into a building services and construction firm but went into liquidation in 1971.

Nick Kingsman’s father and a friend took control of the business with the intention of selling off the property and winding it up.

After re-examining its prospects they decided to try to revive the firm, which Mr Kingsman and his elder brother Stephen took over and “built up from scratch”.

They sold part of the business, Denne Construction, based in Borden, near Sittingbourne, to the Leadbitter Group in 2006.

It is now owned by French industrial group Bouygues after another sale in 2011.

The Kingsmans retained the joinery business, with Nick working as managing director and Stephen acting as chairman.