Alternative to the Prevention of Terrorism Act 2005, that is. The government told us it was essential that the Home Secretary should have the power to deprive terrorist suspects of their liberty. There are serious terrorist threats to Britain. The intelligence services have provided information. We can't be shown the information as it would endanger intelligence agents. British law doesn't allow telephone intercepts to be introduced in evidence in a criminal court. So we must just trust them.
But what does everyone else in the world do? We are not the only target of terrorism. Spain has already suffered a major attack, for example. France apart, most Western nations qualify as infidels for Al Qaida purposes.
So how come Britain is the only "target" nation whose government needs such powers? Are we a bigger target? No. The USA is target #1. Are we a more important target? Well, perhaps 100 years ago, but one assumes Bin Laden is more up to date than that. Are we a softer target? Hardly. Thanks to the boundless generosity of Irish-Americans, we have had 30 years experience of counter-terrorism. If we are not better at it than the average, then we should have been paying more attention.
Other nations admit wiretap/telephone intercept evidence in court. Other nations allow intelligence agents to give evidence. Presumably it's our nation's obsession with "health & safety" that makes us so cautious about our spies welfare? It's surprising that the government feels its possible to provide a "safe system of work" to people infiltrating terrorist networks. The Bond movie franchise will certainly grind to a halt if the producers take this idea on board.
In fact, it should be perfectly possible for agents to give evidence in camera and have their identities protected by the courts. I don't see any particular reason why they couldn't give their evidence from behind a screen under an assumed name ("Bond, James Bond" would do), provided they were satisfactorily identified to the judge.
Simply stated, if the Prevention of Terrorism Act 2005 were necessary in Britain, it would be necessary everywhere else. There is no reason at all why the criminal justice system could not cope with persons accused of terrorism. There is no reason at all why the rules of evidence and procedure could not be adapted by the courts to protect the safety of witnesses. There is no reason at all for this law - other than the political reason of macho posturing before the tabloid press.