I think Peters anticipated that some of her modern-day readers might clue into the solution earlier than the book's characters -- to most of whom, after all, the solution, if they'd ever learned about it, would have been a complete taboo (which is why Cadfael goes to such lengths in conceiling it, too). I still wonder how some of the day-to-day "technicalities" (like personal hygiene and "that time of the month") would have worked out in practice, though, especially inside a monastery. It's one thing to keep this sort of thing a secret when you're traveling with only one companion (who may or may not have guessed the truth anyway), but in a community that leaves little room for the privacy you'd need to conceal this sort of secret ...?
(I think my rating is similar to yours, incidentally.)
Well, I probably wouldn't have clued in so early if other characters hadn't pulled off very similar stunts in some of the earlier books. The exception here is that they were able to pull it off for so long though. Personal hygiene doesn't seem like it would be much of a barrier (monk's robes etc) and I figured menstruation might not be as much of a problem due to diet considerations (fasting and so on) and just the fact that no one would be expecting it, so it's unlikely that anyone would be suspicious.
I mean, women joined the army and the navy and weren't suspected, so it should have been even easier among monks who wouldn't be expected to be as worldly as soldiers?
It was a sin carrying excommunication as a penalty and totally unthinkable, so people definitely wouldn't have expected it. But soldiers on a campaign did "their business" which- and wherever they could, and it's comparatively easy to hide behind a bush or in a group of trees. Whereas monasteries actually had lavatories -- which were anything but private (and there's only so many private places you can find inside a monastery even if you're not using the lavatory). The robes would have helped, of course ...
Well I was mostly thinking about how women used to use their skirts to be able to "go" pretty much wherever since their underwear was far different from ours (petticoats, basically) and thinking that a monk's robe could function similarly, even in a lavatory.
(I think my rating is similar to yours, incidentally.)
I mean, women joined the army and the navy and weren't suspected, so it should have been even easier among monks who wouldn't be expected to be as worldly as soldiers?