There's almost no "action" in the film at all the closest we get is a lobotomized oaf (Warren Clarke, instantly recognizable from his brilliant performance in Stanley Kubrick's "A Clockwork Orange"; this is an actor who can really use his face to good effect) lifting the chairs and table high in the air and eventually absconding with the precious lawn furniture. There are only 5 characters and all the character development consists of revelations and not real transformations. Even so, it's difficult to tell which of the revelations are true and which are simply a façade, because even though these people are inmates at some kind of mental hospital (a fact which, like so much else, is never made explicit but rather must be understood by inferring from casual observations by the characters), they still feel the need to maintain some kind of personal dignity. They show each other respect as well (as the other poster noted, it takes Gielgud's character quite a while to finally let Richardson's character know that his card tricks aren't working too well). Storey's play hits the mark when he shows the 4 primary characters -- Gielgud and Richardson's along with 2 women (Dandy Nichols and Mona Washbourne) one of whom makes up for her insecurity through male attention and the other of whom seems to pay attention to everything and everyone except herself fussing and fretting over who should sit in which of the 2 chairs in the courtyard. I find it really strange, and yet very convincing, that the spectacle is both so pathetic and somehow ennobling. When Clarke's character enters the scene with his implicit violence, they are finally able to restore order to the scene by speaking to him as well, although they grow annoyed when he hangs around perhaps in hopes of being spoken to further. These are characters struggling to hold onto their own sense of belonging in the universe, but deathly afraid of offending or upsetting anyone else's sense of place as well.
I can't say that this is a hugely entertaining film and it will probably alienate many viewers by its lack of action and its down-to-earth conversational style of dialog. However I enjoyed it quite a bit just as a "slice of life" kind of play and I think the dialog and the acting were very well done.