Terrence Hardiman on his Demon Headmaster return: "It's just a cameo – I won't frighten you for too long!"

Bodyguard's Nicholas Gleaves has donned the sinister spectacles to give us his own version of the Demon Headmaster for the new series, but episode 10 will see actor Terrence Hardiman - star of the '90s show - reprise his take on the villain (through circumstances yet to be revealed).

"I just make an appearance for a while, just a cameo," Hardiman tells RadioTimes.com. "So it’s not about me. It’s the new lot, and that’s lovely. I’m not there for long. So I won’t frighten you for too long!"

Now 82, Hardiman admits he was initially "slightly nervous" about playing the Headmaster again after so long a gap. "I thought, well, it’s 22 years since I played that part on television. Are people going to say, 'What the devil is he doing that for? [laughs] Doesn’t anyone else want him to do anything else?'.

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"No, it wasn’t quite like that. But I was slightly nervous about meeting new people. I didn’t want them to start saying, 'Why have we got this old chap in again?'."

Despite some reservations, Hardiman says he found it very easy to slip his spectacles back on and rediscover the wicked Headmaster buried within. "I was allowed to do the same looks, and the same vocal things that I did originally," he explains. "But it’s peculiar how quickly it came back to me.

"And Nicholas Gleaves, who’s a delightful man – it was lovely to meet him – he does it completely differently. I was very impressed. It was lovely to be there with him. I was thinking, 'I feel like he’s my son.'"

Back in the mid-1990s, it was producer/director Roger Singleton-Turner who originally approached Hardiman about playing the sinister schoolmaster who uses powers of hypnosis to enact his evil schemes in Gillian Cross's book series.

"I thought, 'What a horrible character. How lovely. A real villain of a piece. Why not?'," the actor recalls with a chuckle.

All the same, Hardiman had "no idea" that the '90s series would go on to become a sensation, watched in its droves by small children and 'big kids' alike. "I started to be recognised in the street, especially as I lived near schools around here, in North-West London. And there were people – youngsters – looking at me, and shouting out at me, and making fun of me, which is very healthy. It stopped me being too grand!

"But then the slightly more remarkable thing, I found, was that it wasn’t just children who were watching. It was parents and other people, too."

He recalls one incident, being recognised by a shop assistant at his local Sainsbury's. "She said, 'You’re the Demon Headmaster, aren’t you?' and I said, 'Yes, I am.' She said, 'I don’t let my boy watch that.' I said, 'Why not?' She said, 'It’s too scary.'

"I thought, 'But you watch it! So what do you do with your child?' – I didn’t ask these questions, but it made me think: what happens to the boy? Is he told to go off into the kitchen and make a cup of tea while she watches The Demon Headmaster? Maybe that was it..."

The original show ended in 1998 after three series, but Hardiman held onto his trademark tinged glasses. "It sounds as if I stole them, but I didn’t! I was asked by the wardrobe department, “Look after them. You may need them again.'

"So I did, and then I appeared on various children’s morning programmes when they wanted me to come as a guest and to be the Demon Headmaster. And then the glasses kind of got put away into a drawer, and were only brought out for this reboot. I took them back in and used them again. Strange. It was like bringing out an old friend."

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Though he never expected to be playing the Headmaster again, Hardiman isn't at all surprised that the ruthless authoritarian character continues to be popular, in whatever form he might take.

"I mean, he’s a horrible person who wants to rule the world. He believes, passionately and deeply and dangerously, that his way is the way that the world should go. And we’ve had a few people in political positions, haven’t we, in the world, like that?

"I don’t draw any comparisons to what’s going on now [laughs]. None at all. But, you know, we have those people who want to control, and who believe that if they did control the world, or the society that they’re a part of, then things would be better all around. They do believe that..."

The new series of The Demon Headmaster concludes at 5pm today (Monday, 16th December) on the CBBC channel and BBC iPlayer – the entire series is also available to watch on iPlayer