The title appears to be a play on the 1967 Andrea Newman novel, Three Into Two Won't Go, later a film starring Rod Steiger and Judy Geeson.

Date: The weather is very wet, everybody is wearing coats, and there are fires lit in many scenes. So March or (early?) April 1913?

Goof: Sarah's scarf is arranged round her neck differently in the doorstep scene at 3'46" versus the first studio scene at 4'11".

The tune De Brassey is playing on his piano at 5'46" is Chopin's Raindrop Prelude, op. 28, no. 15, composed sometime between 1836 and 1839.

Anton Rodgers (De Brassey) is probably best known to modern viewers from his later TV comedies Fresh Fields (1984-6, and its follow-up French Fields, 1989-91) and May To December (1989-94). He appeared in the Season One Upstairs, Downstairs episode, The Mistress and the Maids. He died in 2007.

Goof: Sarah has trouble with the lid of the teapot (9'26").

Sarah background / Thomas background: De Brassey's house – where the pair take up positions in this episode – is situated in the Wiltshire Downs. They are paid £3 each per week for their services (about £250 in modern terms). Thomas cannot play the piano, but Sarah can to some extent (see also The New Rich).

The song Thomas "plays" on the piano at 30'14" is Let Me Call You Sweetheart from 1910 (music: Leo Friedman / lyrics: Beth Slater Whitson).

Goof?: Thomas: "What the bloody hell do you think you're playing at – moaning around in your room?" Doesn't he mean "moping" around? Or does he say "mooning"? (38'08")

Meg's Diversion (40'09") was a domestic comedy written in 1866 by HT (Henry Thornton) Craven.

The piano tune at 41'33" is Chopin's Prelude In A Major, op. 28, no. 7, composed in 1836.

Goof: At 42'22", De Brassey quotes (Franz) Schubert as describing Chopin's music as: "cannons hidden in flowers." The quote was actually made by Robert Schumann, who knew Chopin well. (Thanks to Stefan Weisman, who spotted this.)

At 42'53" Sarah plays Chopsticks on the piano. The piece was originally called The Celebrated Chop Waltz and was written in 1877 by Euphemia Allen under the pseudonym of Arthur de Lull.

The series ends on a cliffhanger with Sarah attending a funeral – the viewer being left to guess whether it is Thomas or De Brassey in the grave. However, at the time of production, a second season of Thomas & Sarah was already being planned and this would have shown that Thomas survived the fire at the end of the episode and De Brassey perished in it – this is also made clear in the novelisation of this episode.