The title comes from a song by Irving Berlin, written in May 1927 (note: well after the dating of this episode) and first published it on December 2nd 1929. It was introduced by Harry Richman and chorus in the musical film Puttin' On The Ritz in 1930.

Date: Very little to date this episode by, but since grouse is on the menu at The Ritz, it is probably no later than a couple of weeks after the end of the grouse season. So about Christmas-time 1912?

There is so much going on in this episode with regard to names, here is a table summarising the real and assumed characters. ^* = see below for goofs. Spellings of names are not official!
 

Actor	Real name of character	Assumed name/s of character
John Alderton	Thomas Watkins	Thomas Reece-Watkins
Pauline Collins	Sarah	Contesse de Peru/Perdu*
Jonathan Hyde	Charlie-"Boy" Greatley	Charles Scott
Sheila Gish	Cordelia*, an actress	Celia Hebur-Pursey
Peter Howell	Millfield Kennington, an actor	Lord "Buffy" Andover
Monica Grey	Gladys Tate, an actress	Lady "Filly" "Boo" Andover
Charles West	Sir Joseph Weidler
Frances Bennett	Lady Sophia Weidler
Norman Bird	Gilbert Brackley	Barclay (or Berkeley?), the butler
Graham Cull	"Tubby"	Alfred, the footman
Zoe Bright	Dolly	Mary, the maid
Michael Lees	Lord Henry Andover	Henry, the waiter

 
Sarah tells Thomas to put up his "daisies". This from cockney rhyming slang – daisy roots = boots. (2'57")

Sarah background / Thomas background: Sarah once more speaks fluent(ish) French in this episode. She and Thomas are living in Mrs Baggerley's lodgings. (6'04").

Thomas uses the expression "in Carey Street" at 4'56". Carey Street in London contained the back entrance to the Royal Courts of Justice, used for day-to-day bankruptcy cases.

Goof: As "Charles Scott" opens his copy of The Times, we see there is a modern edition sandwiched inside (7'19"). This is presumably to avoid having to duplicate more pages of a vintage edition than absolutely necessary. (The edition in question is from Monday 2/10/78.)

^*Goof: There seems to be confusion over the alias Sarah uses for this episode. Sarah introduces herself (at 8'51") as the Countess of "Peru". Later, at 14'24", the waiter "Henry" seems to say: "Perdu." Thomas seems even more confused and says something which sounds like: "the Countess of Perrer," at 38'14". At 46'56", "Lady Andover" refers to the "Peru" version again.

Thomas background: He uses the alias Thomas Reece-Watkins (or Reese-Watkins).

Thomas misquotes Samuel Johnson at 14'45". The correct quotation is: "A fly, sir, may sting a stately horse and make him wince; but one is but an insect, and the other is a horse still."

Goof?: At 19'42" Lord Andover seems to suggest Theodore Roosevelt is president of the USA. However, William Howard Taft had taken over in March 1909. It is difficult to know if this is a scripting mistake, or simply to indicate Andover doesn't know what's going on elsewhere in the world.

Goof: In this episode, Sir Joseph Weidler is clearly "in" on the con with "Charles Scott" (19'). However, by the next episode (The New Rich), he seems to have mutated into a genuine (seemingly wealthy) financier who is unlikely to be interested in such a trifling scheme.

Goof?: I don't understand the exchange at 20'38". "Celia Hebur-Pursey" remarks that her house is in Eaton Square. "Lady Andover" then replies to her (and Sarah) that: "Oh, you both have houses in Eaton Place!" (To confuse things further, Sarah, in her guise as the countess, then responds: "No ... our town house, it is in London.")

Dr Johnson is misquoted at 40'53": "Sherry is dull, dreadfully dull," should be: "Sherry is dull, naturally dull."

^*Goof: The credits seem to say Sheila Gish played a character called Polly, but this seems to be neither the character's assumed nor real name. Whilst out of earshot of the others, Charles calls her Cordelia (29'24") – this is presumably intended to be the character's real name. To confuse things further, later, again whilst out of earshot, he calls her Celia (48'09").