New Labour*. They dropped the New almost immediately and for a while recently it looked like they might drop it in spirit as well, but apparently not. Their current figurehead is a literal knight of the realm. Not necessarily a conflict of interest, but, well, have you seen him?
Anyway, the purpose of projects like HS2 is to get as much money out of the public purse and into the pockets of politician’s pals as quickly as possible, Labour, Tory or otherwise. If something comes out of it that’s actually useful at the end of it all, well, maybe it’ll garner a few more votes in future? Who cares when you’ve got huge piles of money?