[Nell]

Oh Anne, we've all been there! I couldn't find a gt x lots grandmother for ages. Her name and surname were very common so although I knew she'd been widowed, finding a second marriage was impossible. Finally tracked her down through one of her granddaughters who happened to be visiting on census night - the old lady's surname was changed as of course she'd married again and been widowed again between censuses. She didn't want to be found as she recorded her granddaughter as "visitor" instead of granddaughter.

Some folk just refuse to be on censuses at all.

My great x 2 grandfather, imaginatively named William Williams, has 5 different but plausible birthplaces on 5 censuses, 3 possible baptisms (his age on the census varies) and he and his second wife have clearly decided to disappear after 1901. Not on 1911 census, no likely registered deaths and no burials!