":""Until the Green Party actually come out and either support or oppose they shouldnt be on the list. See http://www.chilterngreenparty.org.uk/news/25/54/Concern-over-route-for-HS2.html"" 
They have come out. 
To reflect that there exists a spectrum of views, I added a section for ambiguous/noncommittal positions. I looked at organisations' statements of position. 
Does The Green Party have a position?
Yes.
Is it noncommittal? 
No. It's support, in principle, for HS2 (specifically mentioned, not just high speed rail ""generally"").

Verbatim from the linked article:
""While HS2 is not our priority for expenditure we do support it in principle."" 

If the stated position changes, that fact can be added.
  

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