The West End show continues its run
Joel Harper-Jackson will be taking on the role of M full-time in Cock following the departure of Taron Egerton.
Director Marianne Elliott said: "Joel is an absolute hero. He is a brilliant and gifted actor and stepped into the role at extremely short notice. Audiences have been standing and cheering and so am I."
Egerton is said to have withdrawn for personal reasons, and had been absent due to Covid.
Co-star Jonathan Bailey added: "Joel is an immense talent and we couldn't be luckier to have him on board. I am proud to continue sharing the stage with him."
Also in the show are Jade Anouka (W) and Phil Daniels (F), while the understudies are Dominic Holmes (John and M), Jessica Whitehurst (W) and John Vernon (F).
Bartlett's award-winning made its London debut at the Royal Court in 2009. The four-hander explores how people can change to be with others.
It received a solid four-star review from Sarah Crompton, who described it as "a challenging, fascinating contest to witness."
Design is by Merle Hansel, lighting is by Paule Constable, sound is by Ian Dickson, composition is by Femi Temowo, movement is by Annie-Lunette Deakin-Foster, associate direction is by Chloe Christian and voice work is by Hazel Holder. Casting is by Charlotte Sutton.
The production continues its West End run through to 4 June 2022, with tickets on sale below.