Many critics over the years have lauded A Number, arguing Churchill created a work of significant intellectual depth with effective economy of style.
In February/March 2009, the play made its Los Angeles/Orange County debut at the Rude Guerrilla Theater Company in a production directed by Scott Barber, starring Vince Campbell and Mark Coyan.
Ben Brantley of The New York Times described A Number as "stunning" and "a gripping dramatic consideration of what happens to autonomous identity in a world where people can be cloned".
However, Brandon praised the final scene as "brilliant" and said that one of its characters "serves as a welcome reminder that it is possible to have an ostensibly normal life", ultimately describing A Number as "one of the more intellectually vital scripts to emerge in the new century" despite shortcomings.
[13] In a 2006 review of a later Churchill work, The Independent's Paul Taylor described the play as one of the best dramas of the new millennium, and as "superbly compressed and economic".
[14] After watching a performance featuring John and Lex Shrapnel, Lyn Gardner of The Guardian dubbed the play "[p]unchy, compact and endlessly inquisitive," arguing that it "is no simple warning against the perils of science messing with nature, but a complex and humane study of parental guilt, regret and responsibility and what it really means to be a father or son.
"[15] Conversely, Jane Shillings of The Telegraph argued, "The highly wrought writing veers at times towards the mannered, leaving a faint sense that the style of Churchill’s play exceeds its substance, and the issue of cloning has lost its urgency".
[16] Don Aucoin of The Boston Globe praised the way the playwright "devotes no time to preamble or writerly throat-clearing, but plunges us straightaway into the play’s central dilemma".
[18] After seeing a 2020 Bridge Theatre performance, Nick Curtis of Evening Standard argued, "If the background logistics are sketchy – who made the human copies, and why?
[15] Matt Wolf lauded A Number as a "beautiful play", and wrote that it "works not least as a thriller or bit of forensic detection, as Churchill plants clues prompting a reevaluation of the narrative at every turn.
"[20][13] Arjun Neil Alim of The Independent stated that "Churchill, a political playwright par excellence, tactfully references current events.
[12] Steve Dinneen argued in City A.M. that the work "is remarkable in the way it so gracefully touches upon the great philosophical questions without ever feeling didactic.
[23] Arifa Akbar of The Guardian said that "Churchill’s linguistic tics – of interruptions and half-finished sentences – create a hyperreal effect and enable Salter’s obfuscation".
[18] Richard Pahl of Northwest Herald billed A Number as an "engaging meditation on human cloning, personal identity and the conflicting claims of nature and nurture".
Pahl wrote that the work "offers intellectual and emotional depth, and illustrates the ways people rationalize bad behavior and unthinkingly objectify others, including their own flesh and blood.