In fact, he was so convincing even ITV got a little confused.
But as well as nailing his voice and mannerisms, the actor had to undergo a major physical transformation to resemble the former Who Wants To Be A Millionaire? presenter.
So just how did this dark, curly-haired actor...
...end up looking so much like this blond, perma-tanned broadcaster?
Surprisingly, no major prosthetics were used
Michael Sheen was against using them as he felt they would “restrict” his portrayal of Chris Tarrant.
Make-up artist Julie Kendrick told PA news agency: “This was a discussion very early on when I first met Michael about whether we did or didn’t (use prosthetics). In my mind, I was thinking we could do some form of prosthetics but Michael very much did not want to.
“He finds them quite restrictive and he also felt that it was his interpretation of Tarrant.”
Actually, there was one tiny piece of prosthetic make-up…
A small mole was added to Michael Sheen’s chin.
Other minor tweaks were also made to Michael’s regular appearance
These included bleaching his eyebrows, the use of a wig, “quite heavy” shading and a tan (obviously).
One of the biggest challenges was disguising Michael Sheen’s naturally very dark hair - including his eyebrows
Julie explains: “[Michael] was very much up for that because Chris Tarrant is very fair and Michael is very dark so in order to make a dark person blonde we had to completely eradicate his dark hair. So it was getting rid of his dark eyebrows and getting rid of his dark hair.
“He’s got such a beautiful head of gorgeous, dark, curly hair and it’s very springy. I plastered it down every single day with some form of hair glue so it was very tight to his head and then we put on some plastic sealer on top and then a bald cap on top of that, so there were three layers before the wig actually went on.”
Copies of Chris Tarrant’s teeth were created but never got used
Julie explains: “I did measure [Michael] for some teeth and we got some teeth made just in case.
“Because Chris Tarrant’s teeth are slightly off centre, when examining all photographs I had of him… that makes his smile very specific and I thought that might be a nice thing to give Michael to use and it’s all about giving actors things they can play with.
“So the teeth could have helped or hindered the performance and we tried them and he didn’t really want them.”
It was still a lengthy process getting Michael camera-ready each day
The actor spent two hours in hair and make-up every day of filming. “It was quite a lengthy process,” Julie explains.
“It was two hours pretty much, we managed to reduce it down to an hour and a half some days.”
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