The story is fascinating, perhaps more for me than most because I live on the site of the TNT factory in Silvertown where Out of the Cage follows the women ‘munitionettes’ who worked packing bomb shells during the first world war, campaigning for better pay and conditions right up to the terrible moment on 19 January 1917 when in the biggest explosion the country had ever seen, the wooden factory became a fireball visible from a hundred miles away

We are on ground made over-familiar by TV dramas – women struggling to make ends meet on low wages, in rank conditions and with exposure to toxic chemicals – and the script is a compound blend of The Matchgirls, Made in Dagenham and even (as Henry Hitchings from the Evening Standard reminded me on our tube home) the Park Theatre’s opening piece last year These Shining Lives set in a radium dial watch factory. Sometimes the speeches of the firebrands calling for strike action sound too modern, at other times lost in dialect and bizarre idiom. Apart from the Irish troublemaker and the posh one, characters are indistinguishable, which is probably why they call each other by their full names all the time, Annie Castledine.

I liked the staging: even in its 90-seat studio, the Park doesn’t stint with production values and there’s beautifully-sawn carpentry and clever under-stage lighting to suggest the factory structure, and some inventive movement and mime coordinated by Simon Pittman against a neat soundscape by John Chambers to evoke the sense of hard industry and urgent moments in the drama when there really are acting fireworks. There’s good close harmony singing, too, and you do derive the impression this piece is struggling to be a musical. Worked for Titanic, set in the same period, so why not?

It’s an ensemble piece with the feel of a feminist collective, but Tegen Hitchens stands out as the poisoned worker desperate to keep her job and protect her children, with nice turns from Katherine Tozer as the statutory upper class woman supporting the commoners, and Jill McAusland as the overlooked youngster whose pay has been unfairly docked.

Although over-long, you care about the outcomes though the campaign for equal pay in the years before women got the vote is even more hopeless than it was in 60’s Made in Dagenham, women didn’t earn equal pay until 1972.

There is more to the history than Alex McSweeney includes in his play: Sir John Brunner, a Liberal politician, grandfather of the Duchess of Kent, and benignly paternalistic owner of the sodium carbonate factory never wanted to make TNT but was coerced by the War Ministry into doing so. Despite the devastating accident, Brunner Mond was one of the richest companies in the business, a founder of ICI, and still operates as part of Tata.  An enquiry suggested negligence of workers’ welfare, but the government suppressed its findings until 1950 when it would have been too late to compensate those affected.