BACK in 1996, Dolly the Sheep was making headlines as scientists succeeded in fully cloning an animal.

This week scientists are claiming that an almost fully-formed human brain has been grown in a lab for the first time at Ohio State University.

They say the brain could transform our understanding of neurological disease. It’s not conscious but the miniature brain – about the size of a pencil rubber, is said to resemble that of a five-week-old foetus. It was engineered from adult human skin cells.

This is not science fiction – this is real life and, of course, none of us really know what is going on behind the scientists’ closed doors.

So Caryl Churchill’s play A Number which delves into the nightmare consequences of human cloning makes for highly interesting viewing at The Nuffield Theatre right now.

This production, directed by Michael Longhurst, was first produced at the Nuffield in February 2014. It transferred to London’s Young Vic in July 2015 where it played to packed houses over a six week run.

Now its original actors, father and son John and Lex Shrapnel play father and son/s in this dark and disturbing play which is staged inside a mirrored cube.

It runs at the Nuffield until Saturday, August, 29.

In a Q&A they reveal more about this brilliant production.

Asked about the cloning issue John said: "The science isn’t really outdated. It was written around the time that Dolly the Sheep was the big global scare and it is about all this happening with human beings and the possibility of genetic restructuring. Caryl Churchill became interested in that and people having different relationships with their father. We simplified it. It’s basically a play about relationships, families and sons.”

The play is set in a mirrored cube and the actors cannot see the audience.

John says: “The whole design of it was to disassociate you and and get your head in the right place before the play begins. The designer Tom Scutt and director Michael Longhurst worked together on Constellations before this. Tom’s idea was that it’s a series of high powered interrogations/discussions like you would have in a hospital or execution room. So the idea was to have a cube with the audience looking in. You are unsettled by the strange music at the start then the shutters open and the audience sees a reflection of themselves. The audience see us but we never see them. Even when we take our bows at the end we can only see ourselves."

Had there been any set changes since it was last in Southampton?

Lex explains: "It’s been refined. A strip of sound proofing has been added to the box and it’s amazing how the acoustics are affected, before we were having to speak over an echo.”

What would be lost from the performance if it had to be done on a normal stage?

John: "It would be a completely different experience. We can’t see the audience but we can hear them – although the only thing we hear is laughter, but it’s not a hilarious play; it’s not a laugh a minute."

Are the mirrors off-putting?

John: “Yes, and that distance from the audience is weird.”

Lex: “When we first rehearsed it was in a box with no mirrors and nothing could prepare us for that. The rehearsal room was very claustrophobic and the huge distraction of seeing yourself reflected to infinity is very disconcerting – especially if you catch yourself doing a bit of bad acting.

“In the time we have spent reworking it we have been able to dig deeper and deeper into the characters plus we had Caryl working with us.

John: "If it had been done in the round it would be very different because we are all we’ve got in that box and we have to concentrate completely on each other, it’s very intense but the feeling would be very different if it wasn’t in the cube.”

Did you draw on your experiences as a real life father and son for this?

Lex: "If I had had a bad upbringing and there had been friction in our relationship it would have been extremely difficult to do but we go for a meal and a drink at the end of the show and everything is OK. We’ve never worked on stage together before this.”

John: “It’s a huge experience to go through and I’d never done a two-hander: it’s been a hugely satisfying experience.”

This is a play about lying – and even the audience is lied to. So what is John and Lex’s understanding of who is who and what happens?

John: “It’s a big ask on the audience this play – but it’s quite a simple play. The language is difficult because it’s very jagged. It’s kind of electric and short-hand.

At the beginning the first line is: 'a number'. He’s told he is one of a number of people. I’m trying to find things out for my son who has come back. He’s told there is a sample and there was an original [son].

Like Greek tragedies – and most American family dramas – its about lying.”

“For us it’s only an hour long but emotionally it is very draining- it’s a very difficult hour .”