life, liberty and the pursuit of geekiness

Oh, MR is most definitely Peninsular War at the very earliest. Terry has been moving Discworld along so that now, after Going Postal, it's in the height of the late Victorian period - and Thud implies that at least child-rearing has moved into the early to mid 20th century. Although Sybil was *always* there. You could stick Sybil in a Sayers book and no-one would blink twice. She could be Peter Wimsey's aunt quite easily.