"it's such a marvellous coincidence to have someone request a really specific pairing [...] in a historical context that you know of "

Isn't it though? I was so very pleased to see the request. As for The Wooden Horse, Eric Williams fictionalized the escape, making a novel out of it with apparent OCs. However, it's only thinly disguised. He was one of the ones involved, and described the method of escape as it really happened. I think you'll enjoy it!