There is a recording of this work (Deakin Piano Trio), but no trace of a published score. Ourtext.co.uk, usually a comprehensive source of reprints of obscure chamber music, doesn't have it, though it has the first two (E minor and B minor, as does IMSLP). Is it published?
David Levy
Parry: Piano Trio No. 3 in G
Re: Parry: Piano Trio No. 3 in G
I would suggest contacting the recording company and ask for their input.