Hugh Armitage is on the set of Poldark series four ready to cause trouble for Ross and Demelza

Actor Joshua Whitehouse, who plays the mischievous and dashing Lieutenant, has posted a video to Twitter of himself magically transforming into Hugh.

"I'm getting better at this," he quips, as he swaps his t-shirt and jeans for a velvet waistcoat and billowing white shirt in a flash.

When RadioTimes.com spoke to Poldark writer Debbie Horsfield about what's to come in series four, she explained that Ross and Demelza strive to “work through this sticky patch” following her infidelity with Hugh at the end of series three.

And yes, she also said that something definitely did go on within those sand dunes...

"What we explore in the fourth series, essentially, is her reasons for this little excursion, shall we say, are many and complex," said Debbie.

“I have often thought in a way it was the perfect storm of Hugh being an opportunist, playing on her sympathies, Ross being occupied elsewhere, Demelza sort of in a way enjoying being wooed and courted in a way which she hadn’t been in the early stages by Ross because she obviously went from being his servant to his wife.”

Here's everything we know so far about series 4 of Poldark, which is likely to air in summer 2018.