OUTLANDER creator Diana Gabaldon has revealed Sam Heughan went from feeling like a rock star to rock bottom — when a boat scene left him sick.

The author has recently returned from South Africa, where the Scots actor is making the third series of the hit historical fantasy drama.

But Sam — worshipped like a rock star by Outlander fans for his role as hunky Highland warrior Jamie Fraser — was swearing like a sailor when he turned green at the gills.

Diana, who is also a consultant on the show, explained: “They have these incredible full-sized ships with hydraulics on set which make them pitch and yaw like real ones.

“Sam had to throw up for one scene as it’s no spoiler to say that Jamie Fraser gets seasick.

“He was standing there with a page of script in his hand looking more than dishevelled, and he said to me he thought he really was going to be sick.

“Sam said, ‘They’ve given me egg whites tinted green with the most disgusting vanilla essence in it. And I have to hold it in my mouth until it’s time to throw up.’

“Of course, they shot the scene over and over again and at about the sixth time, Sam looked at the glass of egg whites before saying, ‘F**k my life.’ So acting is not all glamorous.”

Diana met The Scottish Sun at the plush Cringletie House Hotel near Peebles, which now offers Outlander breaks and even Jacobite-themed weddings and menus.

The US-born writer has become a regular visitor to Scotland since the first of her eight Outlander books was published in 1991. They’ve gone on to sell more than 28million copies and been translated into 39 languages.

Diana’s saga sees Second World War nurse Claire Randall — played by Irish actress Caitriona Balfe — travel back to the 18th century and the Jacobite risings.

The mum of three was working as a professor at Arizona State University and editing a software magazine when she decided to write a novel — and keep it secret from her hubby, Doug Watkins.

She admits: “My husband would have tried to stop me if he found out. Not out of any objection to me writing but out of fear I would drop dead.

“Because at the time I had two full-time jobs and three children under the age of six.

“So writing about Scotland was a complete accident. I never intended to show it to anyone.”

The tourist industry will be eternally grateful she did as Outlander has led to a massive visitor boom for all the locations seen in the first two series.

Doune Castle in Stirlingshire — used as the fictional Castle Leoch — had more than 71,000 visitors last year, up 44 per cent on the previous year.

Blackness Castle by the Firth of Forth — which provides the setting for Black Jack Randall’s Fort William HQ — recorded more than 22,000 visits, up 28 per cent.

But Diana has many more personal stories about the ‘Outlander effect’. She says: “In the first and second seasons there are goats in the pen at Jamie Fraser’s family home Lallybroch.

“Those goats were rented from a Highland hill farmer along with his chickens.

“I was doing a talk at the Wigtown Literary Festival when the farmer turned up to say ‘Thank-you’.

“Apparently the money he got renting his goats saved his whole farm. He even brought the goats to meet me.”

She adds: “The first time I visited the set, where I was filming a short cameo, the Gaelic consultant Adhamh O Broin told me the show was also helping to regenerate the Gaelic language.

“He then said there was a weaving factory in the Borders that was about to shut its doors and go bankrupt until they started making the Outlander tartan.

“Afterwards my husband said, ‘So you’ve elevated the Scottish economy, saved the woollen industry and regenerated the Gaelic language. So what are you going to do next?’

“But the Outlander effect blows my mind all the time.”

The super-smart academic and highly motivated author — who will often write for hours during the night no matter where she is in the world — is a stickler for accuracy.

So it’s no wonder she scoffs at the historical version of events in Mel Gibson’s 1995 Oscar-winner Braveheart.

She laughs: “I mean, there’s artistic licence . . . then there’s rubbish. But I was happy when Braveheart came out around the time of my third book because suddenly all things Scottish became very popular.”

The film and TV rights for Outlander were sold four times over 20 years before it was finally adapted for the screen in 2014 by Star Trek writer Ron Moore, and shown on Amazon Prime in the UK.

Diana, whose books can be more than 1,200 pages long, smiles: “His pilot script was the only thing that didn’t make me turn white or burst into flame.”

Sony stumped up £37million to make the show, which included building Scotland’s first film studio in the old OKI factory in Cumbernauld with help from £4million of funding from the Scottish Government.