Can anyone tell me what these mean...thanks

They are on a pickling fork, I posted previously but it was very grubby, now cleaned and clearer.

Thanks in advance.

A bit of detective work on my own, could it be DEYKIN & HARRISON Silver Plate?

Yes, it is.

Thanks for the confirmation, how would I go about dating it?

You can’t - well not accurately anyway. This link gives a potted history of Deykin and Harrison which may give you some feeling for a possible date range.