Help with maker's mark 1720

Any idea who used the maker’s mark “I.D” within a shield? It is from a rat tail spoon, 1720 I believe. Thanks.

This mark is not illustrated by Grimwade in his book on 1697-1837 London Goldsmiths. However I think that this is almost certainly Isaac Davenport. He had an apparently identical mark before 1697. After 1697 he registered a couple of DA marks in compliance with the new Britannia standard regulations. Your 1720 mark is from the first year of the re-instated sterling standard. As Davenport was still in business he probably dug his old mark out and re-used it.

Phil

Many thanks Phil! The background is much appreciated.