This started off when reading the Cs Goes to It (CS at War) the other week. When the girls are thinking about how the Spy might be getting into the house/grounds, Betty Wynne-Davis and her form (the Fifth) have a whole discussion, where one girl suggests the possibility of a secret passage. Betty is unpleasant and sarcastic towards her, wanting to know why Plas Howell should have a secret passage, and that this girl thinks every old house in England has one, which is clearly an idiotic thing to think.
But the truth is, that Plas Howell is the only house I can think of in EBD's books that does not have a secret passage of some kind.
The Dragon House has the lost staircase, as well a genuine secret passage for priests to escape.
Heather Raphael's house (I've forgotten the name) has the Monk's Passage, to the local church.
Culver/Chudleigh Hold has the secret passage under the rocks to the cave.
I only read 'The School at Skelton Hall' once, but I have vague memories of some kind of secret passage there too - possibly connecting two parts of the house?
The Big House has the passage under the cliffs, which we spend about a term and a half discovering via the stream and the lake, and culminating in the discovery of pirate gold.
Even Plas Howell ends up with Gwensi's secret passage among the yews leading to more unexplored underground passages.
The house belonging to Lorna's aunt does not have any kind of secret, but by EBD standards it is a small, relatively modern house, suitable for a clergyman's widow and her only daughter, but probably not old or important enough to qualify for secret passages.
Can anyone who has read more of the non-Chalets than I have comment on whether this is spread even wider across her books?
I suppose it is a good plot device, and can be used in a number of ways - looking through the list above, each secret passage has its own purpose within the context of the book, but surely, even among stately homes, secret passages can't be as commend as she displays them?