Creators of BBC series that left viewers traumatised when contestant's head exploded explained why it was so shocking

The creators of a BBC series where a woman's head exploded at the end of a quiz show once explained why this sort of thing is so darn effective.

Don't worry, no actual quiz contestants were harmed in the making of this show, though it required a hell of a lot of preparation and misdirection to pull off.

If you want to begin at the end, here's the moment:

What started as a spot of Lee Mack-hosted light entertainment turned into a bloodbath on the quiz show 3 by 3, though if you have already seen this you'll know it's part of the splendid BBC series Inside No. 9, created by Reece Shearsmith and Steve Pemberton.

If you haven't seen it before then the best advice I could give you is to fire up iPlayer and watch the whole show, all 55 episodes of it, and enjoy your new TV obsession.

In the case of '3 by 3' fans were tricked as they thought they were getting an episode called 'Hold on Tight' set on a bus, with promos and previews shot to further the grand deception, only for the BBC to say it had to be replaced at the last minute with this quiz show nobody had heard of before.

Somebody's head exploding, you don't get that on The 1% Club. (BBC)

Of course that was all just a ruse to cover for the real episode and while some Inside No. 9 fans twigged that the name of this quiz show was a big hint, along with the fact that they've tricked the audience before as was the case with their live special, others didn't realise this actually was the real episode until someone's brains were smeared over the set.

In the quiz show itself a trio of teams are competing to build up and win prize money, and the Oakwood family's secret weapon is daughter Catherine (Saskia Wakefield) and her ability to suddenly know answers her comments about a very sheltered upbringing would indicate she'd have no way of knowing.

By the end of the show Catherine seems to have learned a lot about the world and would like to get out and see a bit more of it, though her mother Margaret (Gemma Page) says that'll happen 'over my dead body', which is a horrible choice of words when you've got a daughter with special mind powers.

Just as Mack is wrapping up the episode Catherine gives her mother a hard stare and Margaret's head explodes, throwing the studio into pandemonium.

For the viewers who hadn't realised what they were actually watching, it was quite a shocking ending and was a clear sign that all was not normal as sudden cranial explosions are not generally a feature of a quiz show.

Inside No. 9 is the brainchild of Reece Shearsmith and Steve Pemberton, and they know how to play with audience expectations. (John Phillips/Getty Images)

However, for the creators of Inside No. 9 that was rather the point.

A few years before they put '3 by 3' to screen, Shearsmith and Pemberton explained in an interview they did with Empire how Inside No. 9 could really horrify an audience.

Shearsmith said: "When something is gory in comedy, it’s really horrifying for people because they’re sat thinking they’re going to get… Open All Hours whereas if they’d been geared up for a nine o’clock drama - you could see the most horrendous things in Waking The Dead and all those things that are on earlier and are actually more horrific, but because they’re in the world of drama your mindset is changed in your head and you’re prepared.

"But that weirdly works in our favour as well, because that’s what makes some of the things we do in this ‘comedy’ all the more shocking because we dare to go in places you might not expect in a comedy."

Having bamboozled the audience with the bus episode misdirection (plenty of Inside No. 9 fans would still quite like a bus episode, incidentally) and lured them in with the trappings of a quiz show, it made the moment a head exploded all the more shocking.

The entirety of Inside No. 9 is available to stream on BBC iPlayer, and you'll probably want to make time to rewatch them to pick up on all of the clues and details which make so much more sense the second time around.

Even if you've seen the whole thing you might not be aware of an interactive digital episode they did called 'The Inventors', the interactive version is sadly no longer available but you can still watch the footage on YouTube.