Ahahaha I remember reading this and how nuts it was! Christianna Brand seemed to be of the belief that if one surprise twist is great, five-to-eight would be even better, and she loved stuffing them in no matter which genre she was currently writing in. I still remember Court of Foxes, which began as a relatively straightforward Regency romp about a con artist pretending to be a widowed Marchesa to try and scam a rich nobleman into marriage, and then somehow ended up with more double identities, surprise brigands and birth secrets than you could shake a stick at. Green for Danger was probably her most restrained in this regard and thus her best work, but I do have a fondness for how wild her plots could get.