I can't believe so called "experts" told you this was not possible. Of course it's possible. You probably have loose mortar joints in your brick walls. A hairline crack is all it takes for it to leak.
I'm sure somebody will post a good website or info on repairing this. Because the house is so old and probably historic in nature you will want it done right. After repairs are made a good silicone brick sealer will be a highly recommended.