There are other, more famous, Noël Coward lines – ‘Very flat, Norfolk’ – but not as many as might be supposed. Coward’s was not an especially epigrammatic wit. He disdained Oscar Wilde and his witticisms (‘what a tiresome, affected sod’) and tended to wring humour from a mundane phrase by placing it in an unusual situation. Even ‘very flat, Norfolk’ is not funny, when you think about it, although it is funnier than ‘Norfolk is very flat’. The crisper the consonants the funnier its delivery, and it becomes funnier still when, in the context of its play, Private Lives, you realise that it does not mean Norfolk is flat, whether in the sense of not having hills (which is inaccurate) or of being lifeless (no comment). No, it means ‘your new wife’ – met in Norfolk – ‘sounds absolutely horrendous’.

So I nominate Coward’s most mundane line as one of his best. Eight words. ‘I won’t forget about having the mower mended.’

Walter Hardy is Chief Petty Officer of HMS Torrin, the ship whose destruction is chronicled during the 1942 film, In Which We Serve, Coward’s fictionalised account, which he co-directed with David Lean, of the sinking of HMS Kelly during the Second World War. Walter’s wife, Kath, bids him goodbye at the dockyard gates before he departs for the dangerous sea. In fact, he will survive; she, caught in an air raid, will not. They bid each other what will prove to be a final goodbye, and then she says it: ‘I won’t forget about having the mower mended.’

I think the line is a marvel, partly for being there at all. So mundane a detail, and yet its inclusion in an epic war film, intercut with shots of a sinking ship, suddenly turns the scale and scope of the film on its head. The effect, bizarrely, is not dissimilar to the Duchess of Malfi asking her murderers to remember that her son needs cough syrup, even as the rope is round her neck: a moment of domestic realism at a time of crisis. Coward’s mower has less potential for sentimentality than the Duchess’ syrup, and the slight clumsiness (‘I won’t forget about having…’ rather than ‘I’ll remember to have…’) contributes to the faltering and suppressed emotion. Coward knows that ‘lawn-mower’, as opposed to ‘mower’, and that ‘fixed’, as opposed to ‘mended’, would slacken the sound and rhythm of the conclusion, with those mirrored ms. Life in wartime could rarely be fixed, and broken machinery was mended, not replaced. A year after In Which We Serve was released, the government began its famous campaign: Make-Do and Mend.

The line shows Coward’s understanding of a certain kind of man and his priorities – and it shows Kath’s understanding of them, too, her amused disdain for his fussing, telling him she has remembered before he can remind her. In this moment of farewell she becomes generous: talk of the mower, his terrain, is her parting gift. In a single sentence their home life is glimpsed (he must have a good income, they have grass to mow) and their relationship distilled: unsentimental, bickering, the first flush of romance now settled into a world of comforting and perhaps sexless domestic ritual. Respectability is important. Walter, being Chief Petty Officer, cannot say to his wife what Ordinary Seaman Shorty, in the previous scene, easily says, at the moment of his own departure: ‘Give us a kiss…’ There is social history in the phrase, too: the government introduced petrol rationing for lawn-mowers in February 1940 but it had yet to be banned for private use. The eight words encapsulate the war’s topsy-turvying of traditional roles (the mower and its maintenance are now a woman’s domain) and in them, and the two seconds they take to utter, is all that Kath wants to say to Walter and cannot: that she loves him, that she knows they may not see one another again, that her heart is breaking, and maybe his, too. But they are British, and it is 1941, so they can talk only about the mower, which, even in a time of war, still needs mending. The scene entire is seven lines long. ‘Cheerio’, they say, and he is gone.

T.S. Eliot suggested that Shakespeare’s appending of ‘Ah, soldier!’ to an otherwise finished line of blank verse at the death of Cleopatra’s maid, was something only Shakespeare would think to include. ‘I could not myself,’ Eliot wrote, ‘put into words the difference… if these two words “Ah, soldier!” were omitted… But I know there is a difference, and that only Shakespeare could have made it.’ I feel similar about the mower, which is as essential to Noël Coward’s style as any of his more famous quips, and proof of the dramatic alchemy whereby he can render what his characters mean, and what his characters say, at the same time – even when the two things are entirely different.