The Pirate Party are the only ones serious about challenging ID cards; the tories are just making noises about it for political gain.
The Lib Dems and Greens are also strongly opposed to 'em, and both are more likely to be in a position to be able to assert power and do something about it. I fear the Pirate Party's obsession with 'free (gratis) stuff' also blinds them to the harm it'll do to Free (libre) software.
Free Software has always been at the forefront of Pirate Party policy, and when RMS speaks, the PPUK listens carefully and is careful to ensure that any proposed copyright reform will strengthen Free Software
(e.g. I think the current copyright reform idea from Pirate Party UK is that extended copyright should be conditional on source-code being held in escrow, for release upon expiry of the exclusivity period)