The Neighbours star, who once played Ted Douglas on Prisoner, suggested that if people became invisible there would be a lot more murdered politicians.

"I never thought I'd hear that out of Harold Bishop's mouth. I feel like God just swore," said laughing host Grant Denyer.

His answer gained a huge round of applause from the audience but it wasn't on the board of most popular answers (based on a survey of 100 people).

The round went instead to Wentworth stars of Bernard Curry, Kate Jenkinson, Katrina Milosevic and Celia Ireland, who said they would rob banks.

Smith, who also worked as a writer/director on the show, revealed that he came up with the term "the freak" for character Joan Ferguson. He did not like the original name of 'Massive Ferguson', "No, no you need to come up with one word that creates a chill," he told Denyer.

He was not meant to act in the show but filled in when someone didn't show up.

Smith finished the show in 1986 and went straight to playing the part of church lover Harold Bishop. "We were up in the control room watching the last scene of Prisoner when the powers to be came to me asked if I would do a small part in the new show Neighbours, and I said 'what's that about? About a bunch of people living in a dead end street that won't last long' ... 21 years later I walked away from it."

It was a "complex crowd of people", but mostly his father who helped inspire the character. "I never said it until my mother said 'you're playing dad aren't you?' and I said 'yes' and it was a week after that that she told me I was adopted. So he wasn't my dad but there you go.

"No [regrets] because what a wonderful man he was and what a wonderful woman she was."

Smith also revealed that Prisoner was banned from a female prison at one point when a plot about setting fire to the jail appeared to be copied by real female prisoners a week later.

Prisoner co-star Colette Mann, who played Doreen Burns, said they received a lot of fan mail from prison and the biggest complaint was their characters' lack of styling.

"They used to say that we didn't wear enough makeup. We all thought we were being all fabulous going al naturale, ugly but fabulous. In Fairlea women's prison in Melbourne, where we were based, they all wore lots and lots of makeup," Mann said.

Although Val Lehman played the most bullish character of Bea Smith on Prisoner, she revealed that some of the fan mail scared her. "I had a chap in America who wrote from Alcatraz and he was only allowed one letter a month and occasionally he would write to me."

She said he would write about his daily grind was and asked what her job was like.

"But then we had an incredible endorsement from them saying that we had helped to change the attitude to prisoners worldwide. They were certainly being punished but they shouldn't be maltreated."

The most amusing gift was from another fan, who clearly took the show too seriously and sent Lehman a means of escaping prison. "Do you remember Fiona when actually a fan sent to us a box of chocolate with a hacksaw blade in them so we could get out?" Lehman prompted Fiona Spence (prison guard Vera "vinegar tits" Bennett).

Lehman said they worked 15 hours a day on the show but she didn't take her work home with her. "I haven't killed anyone for weeks," she joked.

Ireland, who plays Liz Birdsworth on Wentworth, went on to tell about the chilling effect Bea Smith had on her as a kid.

"I'm sorry Val but you were the stuff of my childhood nightmares because I remember we could open the sliding door just a crack because we weren't allowed to watch it and I distinctly remember the [sound] of the steam press and mum was so engrossed – we'd be behind where the couch was, my younger bother, myself and my older sister – and we were three little sets of eyes watching."

Fellow Wentworth star Katrina Milosevic told Denyer that her character of Boomer was based on her boyfriend. "He hates it when I say it but I have to say it again; I've actually based my character on my boyfriend Rodney. I love you Rodney so much. He's such a smart man and he's beautiful but he's just a bit like Boomer."

Milosevic says her alter ego is nothing like her in real life so she's always surprised by fans' reactions. "I've been in a headlock a couple of times, which I flounder about in because I'm a bit of a wuss, and I'm like 'oh I'm glad you love the TV show'.

"... I always forget that I'm on a TV show ... so when someone bails you up, I stare blankly and then remember 'oh they know me from the TV show', I'm a bit thick."

Wentworth snatched the victory from Prisoner with an 11th hour minute answer, which earned $20,000 for their charity One in Five, and they went on to make an extra $10,000 in the final round. The Prisoner team still got $10,000 for Positive Women and the MS Society.

Viewers loved all the TV insights:

Wow, what a story from Ian! #FamilyFeudAU— Taking Guard Blog (@sportdeopinion) October 18, 2016