Brahms ' Marienwurmchen song is about a red and black LADYBUG not a ladybird.
Rose said to mend the stocking ladders that sit above the hem. But why mend the ones hidden from view? She should have said BELOW the hem.
As Lady Agnes is knitting with her husband at home, Ivor Novello's song "We'll Gather Lilacs" is playing in the background on the wireless. This song only appeared in 1945 in Novello's musical "Perchance to Dream". However the events of the episode took place nine years earlier, as dated by the death of King George V (20 January 1936) and Oswald Moseley's Whitechapel march (4 October 1936).
Agnes seems to quit smoking once she is pregnant, very unlikely.