According to Pinter's biographer, Michael Billington, the playwright frequently discussed details about the The Caretaker's origins in relation to images from his own life. Billington notes in his authorised biography that Pinter claims to have written the play while he and his first wife Vivien Merchant were living in Chiswick:
[The flat was] a very clean couple of rooms with a bath and kitchen. There was a chap who owned the house: a builder, in fact, like Mick who had his own van and whom I hardly ever saw. The only image of him was of this swift mover up and down the stairs and of his van going . . . Vroom . . . as he arrived and departed. His brother lived in the house. He was a handyman . . . he managed rather more successfully than Aston, but he was very introverted, very secretive, had been in a mental home some years before and had had some kind of electrical shock treatment . . . ECT, I think . . . Anyway, he did bring a tramp back one night. I call him a tramp, but he was just a homeless old man who stayed three or four weeks.
According to Billington, Pinter described Mick as the most purely invented character of the three. For the tramp [Davies], however, he felt a certain kinship, writing "[The Pinters' life in Chiswick] was a very threadbare existence . . . very . . . I was totally out of work. So I was very close to this old derelict's world, in a way."(Harold Pinter 114–17).
For earlier critics, like Martin Esslin, The Caretaker suggests aspects of the Theatre of the Absurd, described by Esslin in his eponymous book coining that term first published in 1961; according to Esslin, absurdist drama by writers such as Samuel Beckett, Eugène Ionesco, Jean Genet, and Edward Albee, and others was prominent in the late 1950s and early 1960s as a reaction to chaos witnessed in World War II and the state of the world after the war.
Billington observes that "The idea that [Davies] can affirm his identity and recover his papers by journeying to Sidcup is perhaps the greatest delusion of all, although one with its source in reality"; as "Pinter's old Hackney friend Morris Wernick recalls, 'It is undoubtedly true that Harold, with a writer's ear, picked up words and phrases from each of us. He also picked up locales. The Sidcup in The Caretaker comes from the fact that the Royal Artillery HQ was there when I was a National Serviceman and its almost mythical quality as the fount of all permission and record was a source.' To English ears," Billington continues, "Sidcup has faintly comic overtones of suburban respectability. For Davies it is a Kentish Eldorado: the place that can solve all the problems about his unresolved identity and uncertain past, present and future" (122).
About directing a production of The Caretaker at the Roundabout Theatre Company in 2003, David Jones observed:
The trap with Harold's work, for performers and audiences, is to approach it too earnestly or portentously. I have always tried to interpret his plays with as much humour and humanity as possible. There is always mischief lurking in the darkest corners. The world of The Caretaker is a bleak one, its characters damaged and lonely. But they are all going to survive. And in their dance to that end they show a frenetic vitality and a wry sense of the ridiculous that balance heartache and laughter. Funny, but not too funny. As Pinter wrote, back in 1960 : "As far as I am concerned The Caretaker IS funny, up to a point. Beyond that point, it ceases to be funny, and it is because of that point that I wrote it."
Pinter's own comment on the source of three of his major plays is frequently quoted by critics:
I went into a room and saw one person standing up and one person sitting down, and few weeks later I wrote The Room. I went into another room and saw two people sitting down, and a few years later I wrote The Birthday Party. I looked through a door into a third room and saw two people standing up and I wrote The Caretaker.