www.925-1000.com

OK. I think I just answered my own question.
This mark seems to be the one!
Scroll down to Thomas Daniell - 1784

http://www.loreman.org/silveroantikt/uksilver.htm

The letterforms are not exactly the same and, of course, there is no way to verify the year, but it's close.
.

This is a good possibility. I don't have access to a directory of maker's marks so I don't know if Thomas Daniel registered a mark with a bullet between the letters or not.
.

I inherited a set of 6 Hanoverian teaspoons with scroll decoration on the backs. There is no date mark, as you can see in the photos. I believe the mark to be T-D, though it is quite disfigured on some of the spoons. The style of the lettering in the maker's mark is quite different, perhaps earlier,...