Thanks for taking the time to do that John. I went through and checked all my opalescent pieces last night and none have a base like this vase. All have a base that looks like the body i.e. no little bits of white showing including in my oldest pieces. Perhaps the white frit used to create the white effect on the vase was only used at a certain time frame or place which might eventually help date it. I've only gone down the older route because it arrived with a piece that dates to 1700s, so thought worth checking out.
Agree on the handles.
m