Some of the early Steed and Gale episodes were remade for the Steed and Peel era : series 3 episode 23, "The Charmers" was remade into "The Correct Way to Kill" for this series.
When Steed is cutting the ties binding Olga, he pauses before cutting an Old Etonian tie, saying "that's my old school tie". Patrick Macnee was indeed educated at Eton.
That's the second time where Steed gets a female sidekick other than Emma Peel. The previous time was in Girl From Auntie episode.