Chris Tarrant's grandson duped by Michael Sheen in 'Quiz'

Chris Tarrant’s grandson was utterly convinced by Michael Sheen’s performance in Quiz.

The Welsh actor is playing the gameshow host in the new ITV drama, which tells the story of the infamous Major Charles Ingram coughing scandal on Who Wants To Be A Millionaire?

Tarrant’s daughter, Heart radio DJ Fia Tarrant shared a video clip of her son watching Sheen on television saying: “It’s grandpa. It IS! It IS grandpa.”

She revealed he had never watched presenter Tarrant, 73, on TV before.

Read more: Chris Tarrant says Who Wants To Be A Millionaire cheats are 'guilty as sin'

Fia tweeted: “Monster has never seen his grandpa on TV before so I thought I’d see what his reaction would be seeing @michaelsheen.”

Sheen, 51, replied: “Best review I’ve ever had.”

The Good Omens star had already won the approval of Fia and her brother, Radio X DJ Toby.

He tweeted after watching the first episode of the ITV drama: “Really enjoyed #Quiz tonight, looking forward to the rest of it @michaelsheen as expected is brilliant as Dad...

“To be fair, he's so good he'd probably be convincing as my Norwegian auntie Tina.”

And Fia previously wrote: “I don’t think I’ve fully appreciated an actors art until I saw @michaelsheen last night. He’s not only perfected dad’s mannerisms, he’s got the voice quite spot on too! Phenomenal performance can’t wait to watch the rest!”

Sheen has made a name for himself playing recognisable British stars on screen having portrayed Tony Blair (The Deal/The Queen/The Special Relationship), Kenneth Williams (Kenneth Williams: Fantabulosa!), David Frost (Frost/Nixon), and Brian Clough (The Damned United).

The Hollywood actor as Chris Tarrant in the three-part drama about Major Ingram and his wife Diana’s attempts to cheat the popular TV quiz in 2001. They took home the jackpot after planting friend Tecwen Whittock in the audience so he could cough when Ingram read out the correct answers.

Spooks star Matthew McFadyen is playing Major Ingram and Fleabag’s Sian Clifford will appear as his wife. The drama, directed by ward-winning filmmaker Stephen Frears, also stars Peaky Blinders’ Helen McCrory will also be in the series as the Ingram’s lawyer Sonia Woodley QC.

Read more: 'Quiz' finale chooses to 'ask the audience'

Hit quiz show Who Wants To Be A Millionaire? sees contestants answer multiple choice questions which increase in difficulty as the prize money stakes rise, with the help of several lifelines, including Phone A Friend.

Ingram scooped the top prize of £1 million in September 2001 but the show’s production company Celador refused to pay out when it suspected he was guilty of cheating.

Charles and Diana Ingram, along with Whittock, were all found guilty of "procuring the execution of a valuable security by deception" in 2003 and were handed suspended prison sentences.

The Ingrams maintain their innocence to this day and are said to be working on an appeal.