When Tony Harrison’s verse play, which examines the use and misuse of two weapons of mass destruction during the First World War, was first seen at the National Theatre in 1992, the use of gas in conflicts seemed a thing of the past.

This all-female production — the first London revival of the play —arrives just as Syria’s President Assad is expected to attack the militant and civilian population of Idlib with chemical weapons such as gas, the very death method first deployed on the killing fields of Europe.

Yet despite such unhappy modern relevance it is hard to see what theatre company Proud Haddock thinks is essential about the play. The central figures are the Jewish scientist Fritz Haber whose techniques for extracting nitrogen from the air allowed for the production of fertiliser, increasing farmers’ yields and thus feeding millions. Meanwhile the American-born British inventor Hiram Maxim dreamed up the first fully automatic machine gun, the ammunition for which depended on the invention of TNT which was also the result of extracting nitrogen.

If all this sounds more like a lecture than a play then to large extent that is what you get — only in rhyming couplets. An awful lot of energy and effort is expended on a commonly known truth, that science can be used for the good of the people and also to kill them. If this banal little observation was the seed of Harrison’s play then it’s hard see why among all the examples available to him — nuclear physics, biology — he chose Maxim and Haber.

There is a possible answer in the second half of the play which focuses on Haber’s Jewishness. Much against the wishes of his Jewish wife Clara, Haber developed his technique for producing fertiliser to come up with an antidote to Maxim’s machine gun — gas.

The antisemitic Kaiser “would never have used you if he could find/ A gentile genius with an inventive mind,” says Clara, which is a fair enough point. But Harrison is apparently so obsessed with with the fact that a Jew was the first to develop poison gas, he can’t help but dwell on the fact. “If he could find and Aryan as brilliant as you/ Do you think he’d bother with a bloody Jew?”, says Clara, who obviously thinks the point worth repeating.

Clara, the first German woman to be awarded a doctorate in chemistry, killed herself because of her shame that her husband used his knowledge as a scientist to invent the weapon of poison gas. This is its own moral judgement on Haber. But Harrison adds his own with the smug certainty of what came later, piling more guilt on Jewish Haber than he does on Maxim.

Granted, Haber is portrayed as believing that his poison gas will end all war and therefore save more lives than it ends. But the suggestion here is that Haber deserves a greater burden of guilt because two decades or so later, Jews like him were gassed by the Nazis. And I don’t want to defend Haber any more than Clara did, but that’s not fair. Nor is there any evidence that Haber’s invention aided the Nazi genocide.

There are are some interesting historical facts here. The square rounds of the title refers to the more painful bullets that were reserved for non-European foes such as the Turks. And the young cast in Jimmy Walters’ inventive and at times playful production are committed and excellent throughout.

But the play itself is little more than a display of virtue signalling in the part of its author, and if it’s not revived for another 30 years it’ll be no great loss.