The title of this episode comes from the 1914 song called Keep The Home Fires Burning (Till The Boys Come Home), music by Ivor Novello and lyrics by Lena Guilbert Ford. It was extremely popular during both wars and was often sung by the Allied troops. (Idea for this entry from Darrel C Karl.)

Rose previously met Gregory Wilmot in A Perfect Stranger in Season Three.

Date: The events of A Perfect Stranger are said to be two years ago, and given the weather on view – sometime in the spring of 1916.

A temporary cook, Mrs Ganton, replaces Mrs Bridges in this episode (who is away with relatives). Mrs Ganton only ever says: "'Evening, Rose." (1'17")

Mrs Bridges background: She has a married sister living in Great Yarmouth (3'38"). This may, or may not, be the same sister as mentioned in What the Footman Saw. Compare with Why is Her Door Locked? which said she had no relatives.

Goof: Hudson magically appears in the hall to see Richard off without being rung for (5'47").

There is a jump in the picture in most modern copies of this episode at 8'56" – Hudson's position changes suddenly as he moves across the servants' hall. Older copies (e.g. the US DVDs) do not have this jump.

Goof: Hudson seems mildly surprised that Gregory is in the Anzacs. Since Gregory is Australian, what corps did he expect him to be in? (10'04")

The location shooting for the various bus rides in this episode took place in and around Barnsbury Square and Thornhill Square in Islington, London.

Goof: As Gregory waits for the bus, you can see a single yellow line which has been blacked out near the kerb of the road (12'05").

Goof: After broadcast, the production team received a letter from viewer JGE Pearson stating: "The omnibus on which Rose was a conductress was an S-type and this showed up quite distinctly. This type did not exist during World War One and did not appear until the 1920s. Those of us who lived through those times know there was only one type in operation – the B-type." John Emery, the designer, claims the bus used was a K-type.

Goofs: Various television aerials are briefly visible on houses in the background during the bus ride (12'22",13'26",13'29").

Goof: As Gregory nears the end of his bus ride at 14'02", on the right-hand side of the shot you can see the bus pass a large building with fluorescent strip lights burning in every window. These did not appear until the end of the 1930s. (The building is the West Library on the junction of Thornhill Square and Bridgeman Road.) (Thanks to Chris Ivory for sending this one in.)

The "End of Part One" caption for this episode is shot on film, rather than in the studio (19'16"). This is one of only two times this was done (the other is The Joy Ride).

Goof?: Gordon Jackson: "Well, I hardly think political discussions are revelant at the moment." (relevant) (20'44")

The song on the gramophone is He'd Have To Get Under – Get Out And Get Under (To Fix Up His Automobile), written in 1913 (music: Maurice Abrahams / lyrics by Grant Clarke & Edgar Leslie).

Goof: The mug next to Gregory's hat at 41'13" has vanished by 42'04".

Goof: Mr Hudson suddenly has a newspaper in his hand (49'01").