'This Country' casts A-list star as Kurtan's nan: which star is behind the role?

The actor's face was pixelated on the show and credited to an 'Elvira Presley'. (BBC)

This Country featured a high-profile actor in a cameo role in the latest episode of the third and final series of the BBC mockumentary, however, their identity is being kept tightly under wraps.

While Kurtan's (Charlie Cooper) grandmother is oft discussed and has been heard on the programme, she made her first physical appearance on Monday night's episode albeit with a pixelated face

While Kerry (Daisy May Cooper) was showing the documentary crew her outfit, Kurtan's grandmother came out to rant and rave at the filmmakers with the part attributed to the pseudonym of "Elvira Presley" in the credits.

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It has been confirmed that an A-list actor assumed the role, with fans left playing the sleuth as the guesses have rolled in with famous faces like Helen Mirren, Julie Walters and Cate Blanchett being thrown into the mix.

One big name that's got a lot of backing is Tilda Swinton and some clues have been offered up which make the acclaimed actor look like a dead cert.

The show's director Tom George treated fans to a set of clues alluding to the identity of the mystery person. He shared that the individual in question was not from England, flew in especially to do it, that they had never them before the day and that they have a "very creative partner".

It just so happens that while Swinton was born in London her family are historically Scottish and it’s where she has resided for decades, plus her partner Sandro Kopp is a painter.

In addition, Daisy May Cooper starred as Peggotty alongside Swinton's Betsey Trotwood in The Personal History of David Copperfield meaning she has a connection to the programme already.

The clues have pointed to Tilda Swinton being behind the role. (BBC)

However, others also suggested that it could even be US actor Meryl Streep, whose husband is a sculptor.

But viewers might be in for a wait when it comes to confirming the mystery - if the actor is verified at all.

"We’re not telling you who Kurtan’s nan is,” BBC Three tweeted ahead of the episode and the cast have remained tight-lipped, so it seems as though the guessing games will keep on going.