I'm very surprised to hear that such an old house has cavity walls. I would expect solid brick walls in Flemish bond. My house is 1970 and has them, they were much more common after the war.
Old Victorian terraces in the North East where I live have them because they were built by very wealthy shipyard owners so they could afford to put up high quality housing, and they needed something to keep out the damp. Cavity walls made from two layers of brick with iron ties were the solution.
