Can someone advise about these hallmarks please?

I would love to know more about this little hand made jug. If one of you gurus could advise.

Many thanks

Kind regards

This is a London sterling silver hallmark with the date letter “d” for the assay year 1779/80. The maker, I·I, is Joshua Jackson.


My goodness Phil, this is lovely to read.
What a surprise.
Thank you for your expertise and time taken to reply.
I think it’s time I re- asked the family to keep this little jug it has such an age it should stay with the family.
It is quite a lovely little jug.
Kindest regards and thank you.