This is a 1998 revival of Oh, What a Lovely War!, the musical that was one of the most famous productions directed by the extraordinary Joan Littlewood and her company Theatre Workshop.
It was a savage satire based on World War I. Written by Littlewood in 1963 it ruthlessly exposed the horrors of the trenches and the callous incompetence of the ruling aristocracy that sent thousands of men to their death. The whole thing was dressed up as an Edwardian music hall show performed by Pierrots who were popular in seaside pier shows.
Theatre Workshop was a radical left-wing theatre company which aimed to bring theatre to the people. Much of their work was created through improvisation in rehearsal. As part of the process of creating Oh, What A Lovely War! the company invited locals to come and see the work in progress and ended up incorporating some of their stories into the production.