Hi Don,
I agree, if it is a PH cane then it is for Peter Holmes, formerly of Selkirk Glass (which he founded) and now of Scottish Borders Art Glass.
His weights are not always engraved with the relevant information onn the underside (I have a few in my collection and seen others).
I am not sure who DH could be, though. If it were AH, it would Andrew Holmes - the son of Peter Holmes - He is also at SBAG.
SophieB