Retired, self-sufficient parents want long term residency

We are self-supporting, retired Americans who very much want to join our daughter and grandson (both have dual USA-British citizenship) in the UK. It looks like this would have been possible a few years ago, but I can't find a way to do that now. The closest I seem to be able to get is residency in Ireland, a country that is kind enough to have retiree options. Anyone know a way for us to reside in the UK as retirees that I am overlooking?