Your correspondent E. D. might have gone much farther back for an example
of the use of the word _party_ for a particular person. In the _Tempest_,
Act III. Sc. 2., we have:
"_Cal._ I say by sorcery he got this isle.
From me he got it. If thy greatness will
Revenge it on him--for, I know, thou dar'st;
But this thing dare not.
_Ste._ That's most certain.
_Cal._ Thou shalt be lord of it, and I'll serve thee.
_Ste._ How now shall this be compass'd? Canst thou bring me to _the
party_."