DEREK Crawford Munn offers a delighted smile as he talks of wearing a threadbare Third Reich uniform and raising an aged, wobbly arm in Nazi salute. What actor wouldn’t want to play Rudolf Hess in an acclaimed play about his life?

“It’s a great opportunity,” says the former River City actor and veteran of 25 years in the acting trenches. “This is one of the dream roles that rarely comes along in a career. In fact, I’d say it’s the most demanding role I’ve ever undertaken. And I really plan to enjoy every moment of it.”

Hess, Michael Burrell’s one-man play about Hitler’s right-hand man, is certainly is a dream role. Hess was a Swastika-waving madman, a man who created the Nuremberg Laws of 1935 which stripped German Jews of Germany of their rights in the lead-up to the Holocaust.

However, on May 10 1941, Hess decided to fly himself to Scotland and form some sort of alliance with the Duke of Hamilton, whom the German reckoned could create a platform for peace talks. What was Hess’s motivation? A dramatic change of conviction? Survival?

“There are more levels to the play you would first imagine. And while part of the challenge of this piece is to reveal the Nazi story you have to remember Hess was a human being.”

The actor smiles in anticipation of the next question. “Yes, Hess was an extreme human being of course. But the challenge is to reveal why he became so extreme.

“There was also the controversy about his death (in Spandau prison in 1987) which was claimed to be a suicide.”

Or was it? Why would Hess take his own life at the age of 93? Surely, someone facing life in prison would have taken that route earlier?

“Yes, the play suggests he had no intention of killing himself. Why would he? Suicide has never been confirmed. And it wasn’t until after his death questions were asked about how Hess came to power under Hitler and why he chose to fly to Scotland to establish peace.”

The play was written in the late 1970s, but Munn maintains it’s still highly relevant today.

“It’s fresh because of the rise of right-wing groups across Europe. Even UKip, for example, has been throwing people out because of their right-wing views. And you just have to look at the Facebook page I’ve put up to see those attracted to Hess’s name. It’s incredibly worrying.”

There is another theme which underpins play: should prison ever be all about punishment?

“At one point in the play Hess says: ‘How can I change if I’m not allowed to replace my dreams with anything?’ What the play asks is the point of imprisonment without rehabilitation.”

Munn hasn’t been on stage for four years (working in film) since he fronted his own production of Macbeth.

“I’m ready to throw the actor’s armoury at this one,” he says, with a defiant note in his voice. “I’ve been reading and watching everything there is out there about the Third Reich, submerging myself in the world. The subject needs it. I’ve also lost about a stone in weight, thanks to working out with a fitness trainer, to be able to look the part.”

Munn, who played gay DCI Eddie Hunter in River City, has the experience to portray such a complex character. The star of Scots film Fast Romance has toured in Barnum and ‘done everything from Shakespeare to circus.’ He even toured in South America with Circus of Horrors.

Growing up in Inchinnan in Renfrewshire, Munn was “a natural show-off”, yet didn’t became an actor until he was thirty, pushing off the parental pressures which demanded a less precarious career.

“I was an apprentice plumber until I was tall enough to join the police. But I’d always wanted to act.”

And now he’s an infamous Nazi, with a perfect German accent. “Not quite,” he says, smiling. “Thankfully, Michael Burrell wrote the play in such a clever way that the accent sounds German - but without a German accent being put on.

“That doesn’t mean it’s not a hugely demanding role and it’s not daunting to play such a big character. But having said that, I’m loving every single moment of it.”

• Hess, Websters Theatre, Great Western Road, Glasgow, September 7-12.