He struck fear into the hearts of millions of kids with his curt, clipped voice, billowing gown and piercing eyes. We could never quite put our fingers on it, but every time we saw him we started feeling so sleepy...

Cleary born to play steely, scary characters, Terrence went on to star in Dr Who twice – once as Rassilon, founder of Time Lord society on the planet Gallifrey and it's first Lord High President (fancy), and then again as Hawthorne, leader of the Queen's government in the episode The Beast Below.

The older Hunter brother, Lloyd was one of five students at school who are immune to the Headmaster's hypnotic powers. At first he's deeply suspicious of Dinah, but proves himself to be a brave and loyal friend.

Gunnar is still acting, enjoying steady TV roles and voiceover work since his return to the profession in 2010, including War Horse, The Tudors and Mars. He's also recently become a dad.

Harvey was loveably bumbling, forever taking his cue from his big brother, although so warm and trusting that he's quick to befriend Dinah – even against his brother's wishes. He was a founding member of SPLAT and also immune to hypnosis.

Thomas hse moved entirely away from acting, writing in his Twitter bio that he's a "failed actor" - awh. He does seem to be doing incredibly well for himself as a digital consultant and entrepreneur though, even founding his own company. Here he is with a duck.

Dinah Hunter joined the family as Dinah Glass, a foster child, and when she proved to be vulnerable to the Headmaster's powers she was quickly branded "one of them" by SPLAT. However, she bravely fought the hypnosis and ended up being a core, valued member of the team.

Frances has had quite the career overhaul, continuing acting up until 2015, before training to be a dentist, and now running her own careers coaching business for trans and non-binary people. Here she is starring as DI Lisa Hudson in indie flick Souljacker.

Mrs Hunter was the big-hearted wonder mum who decided to foster Dinah, and was forever checking in on her kids. She's blissfully oblivious of the goings on at the school, taking her boys' reports with more than a pinch of salt.

Tessa was already a well-known actor before she was cast in The Demon Headmaster, having played Del Boy's other half, Raquel, on Only Fools and Horses for many years. Her most recent TV credit is in Grantchester, which returned this year.

Rose was the SERIOUSLY creepy head prefect who kept a vengeful watch over SPLAT and reported ALL indescrepencies back to the Headmaster. Almost as scary as the man himself.

Katherine is now living in New Zealand, and describes herself on her own website as an "actor, artist, and film/theatre & visual arts industry professional with over 20 years experience." Phew!

The youngest member of SPLAT, Ingrid by no means lacks bravery and sass, but is prone to sulking if she doesn't get her way. Like the other members, she's immune to the Headmaster's hypnotism.

Kristy is the only other member of SPLAT we've managed to track down, with Ian and Mandy both dropping off grid. According to her Twitter she's still acting, but has also been studying for a psychology degree and posing with cute dogs.