Caryl Churchill’s new play brings to mind experiments made in the early 1900s. Behavioural scientists would take orphaned identical twins and bring them up, one in an orphanage, one in a loving home and compare the results. These experiments on genetically identical individuals were soon banned as unethical.

The Royal Court assembled their dream team: the acting prowess of Sir Michael Gambon and Daniel Craig, who plays Paul Newman’s son in The Road to Perdition, the director Stephen Daldry and the writer Caryl Churchill. Director and author are repeating the partnership forged in Far Away.

A Number is about the three sons of Salter, Michael Gambon’s character. All three are played by Daniel Craig. There is Bernard One, aged forty, the original. He is aggressive, violent and has nightmares. Bernard Two, who is thirty five years old, exhibits no aggression but worries about being “just a copy”. Michael Black, also thirty five, is from the same “batch” as Bernard Two but has been brought up by different parents. Bernard One was neglected by his father after the death of his mother and was taken into care at his father’s request. Salter is not a good father to Bernard One and, unusually in parenting, he gets a chance to try again with Bernard Two but is unaware that Bernard Two is one of “a number”. Salter redeems himself with the raising of the second child but like Cain and Abel, jealousy will intervene.

Churchill’s writing is full of interrupted and unfinished sentences. It is all the more credit to the cast and the director that they deliver the prose in a completely natural and believable way. It’s likely to be a bit confusing, unless you are prepared for there to be three characters played by Daniel Craig, as each clone looks identical and wears identical clothing. This is a frightening brave new world of scientific experiment with little thought as to the effect on the cloned children and their progenitor.

Michael Gambon is one of the most watchable actors on the London stage. A large presence with a softly murmuring voice. His character must show himself sometimes trying to wriggle out of his responsibility, sometimes to be reassuring. His reaction to his son’s revelation of the secret batch is to talk about litigation and hundreds of thousands in damages rather than the psychological impact on the son. Gambon conveys all this ambivalence and gives us an insight into some of the characteristics his sons may have inherited from him. He probes for differences between the sons, curious as to how disparate they are and is by turns tender, contrite, anxious. In order to meet Michael Black for the first time, he slowly puts on a tie, the formal wear reflecting the seriousness of the meeting.

Daniel Craig has the interesting but difficult triple role of three sons who look similar but who are very different. As directed by Daldry, it works, and baby face Craig conveys the essence of each man, one dutiful, one criminal and one detached.

Is A Number a worthy vehicle for this assembled talent? Almost.