The Third Floor Flat became the fifth episode of Poirot's first series. It was adapted from the short story published in 1929. Scriptwriter was Michael Baker, in his first of three Poirot scripts, and Clive Exton as a script consultant (notice how the production team are slowly letting other writers in on the job, under the watchful eye of Exton). The director was Edward Bennett, who had already directed the first two episodes of the series.
Script versus short story
The script stays remarkably close to the (rather thin) short story. There are some additions, but most of the added scenes are based on tiny references in the source material. I've noticed that some bloggers claim that the opening scene of Patricia and Mildred dancing is nothing but padding, and of course, to an extent it is, but Patricia does mention in the short story that the letter from Mrs. Grant is probably a complaint about the loud music from her piano, so to have them dancing to a record is more than acceptable in my view. Also, the fact that Mrs. Grant has just moved in isn't in the original story. In fact, you could almost get the impression that she has been living there for some time, without knowing that her rival lives right above her. So again, Baker's change makes complete sense (and, the change gives us some wonderful glimpses of Whitehaven Mansions!).
Now, of course, the main change, really, is that the unnamed residential block in which Poirot rents a flat is changed into Whitehaven. A very sensible decision. First, why would Poirot live anywhere else, now that he's established in Whitehaven? Second, why on earth would he take the name of O'Connor (and pretend to be Irish!)? I mean, out of all possible disguises, that is probably the worst he could have chosen (and dare I say, it does sound a bit out of character for him to choose such a lousy disguise!). Also, it makes much more sense to have Patricia be aware of his presence. I mean, if you were Hercule Poirot's neighbour, you'd probably know! Another important change is the introduction of Poirot's cold. Now, that's also based on the text actually, because it's how Poirot tricks Donovan into smelling the sedative, so again, a perfectly sensible addition.
The changes I've mentioned so far are all at least partly based on the source material. In addition to these, Hastings, Japp and Miss Lemon are added (which has become the norm by now). Miss Lemon's part is small, but sensible, in that she gets to help Poirot with curing his cold. Hastings doesn't get much to do either, apart from the added chase scene towards the end - and of course the devastation brought on by the destruction of his beloved Lagonda. Japp replaces Inspector Rice from the short story, and I'm not complaining. I do realise that they need to have a basic family unit, as Exton has described it, to make the series work. And of course, it adds to the development of the camaraderie between Poirot, Japp and Hastings. There's also an added section of the episode in which Poirot and Hastings, along with Patricia and her friends, attend a play. This is a nice addition, both because Hastings takes Poirot to a play like this in Christie's novel Dumb Witness, and because it explains where Patricia and her friends had been before they return to the flat (in the short story, it's just assumed that they've been out for the evening). As an aside, a very similar scene takes place in the adaptation of The Clocks, in which Poirot attends a stage version of one of Ariadne Oliver's books, 'The Good Samaritan' (another nice bit of continuity of sorts within the series' run). Any other changes I haven't mentioned are so minute and mostly based on the text, so I won't go into detail about them.
Directing, production design, locations and soundtrack
Edward Bennett's direction is competent as usual. In this one, I particularly love his use of the location, with the rather memorable crane shot that follows the building from the window of Mrs. Grant's flat in 36B through Patricia's flat in 46B to Poirot's in 56B. I have always wondered whether that was shot on location at Florin Court or in a studio of sorts, but I guess they must have shot it on location - if not, then they really had some fancy special effects!
Now, the star of the show here, really, is Florin Court, that magnificent 1930s building doubling as Whitehaven Mansions. While I rewatched this episode, I realised how lucky the production team were when they discovered this gem - and found it to be empty of tenants! The story is quite remarkable, really. (See the documentary Super Sleuths or Peter Haining's book on the series). In fact, this particular episode could probably not have been shot in exactly the same way had it not been for the fact that they discovered this temporarily empty and newly restored building. Yes, the flats seen on screen are constructed sets, and the staircase is probably in a completely different building, but there are so many shots - in this and other episodes of the first series - looking in on the action through the windows or driving past the apartment block in the square in front of it, that probably couldn't have been done if the block was occupied.
The soundtrack to this episode is actually quite memorable. Sadly, Gunning's score for this one has not been released. As to the other bits of music - the record Patricia and Mildred are dancing to and the song they're singing in the staircase, I haven't been able to track down much information. The song they're singing is 'Life is Just a Bowl of Cherries' from 1931.
Actors and characters
There some nice character development on Poirot's part here. First, of course, we have his hypochondria, the very serious cold that turns out to be not as serious after all. I love that he's wearing all those layers of clothes (again, spot on from Christie's stories). Notice the slight change in voice as Poirot gets better (Suchet strikes again!). Second, there's the nice story about the girl he fell in love with who couldn't cook (though we can't really trust him with these sort of stories, he is known to invent whatever story suits him, it's still a nice touch and a slight sign of his lamentation on his loneliness that will grow in the years to come). Finally, there's his matchmaking trait. This is a particular favourite of mine. In several of Christie's books - and in quite a few of the adaptations - Poirot takes on the role of matchmaker/Cupid, like with Jimmy and Patricia ("Go to Mlle. Patricia, Jimmy"). See also the adaptations of How Does Your Garden Grow?, Murder on the Links, Sad Cypress, Mrs. McGinty's Dead, and The Clocks.
Of the guest actors, Suzanne Burden (Patricia Matthews) stands out with a lively and vivacious performance, and Nicholas Pritchard (Donovan) somewhat manages to awaken some sympathy for his character when he confesses to the crime.