UK Prime Minister David Cameron unveiled plans to fill what he described as “the gaps” in Britain’s anti-terrorism efforts.  But the Tory PM was forced to shelve certain portions of the plans after political and legal opposition, and failing to secure the support of his Lib-Dem coalition partners.

“It is abhorrent that people who declare their allegiance elsewhere can return to the United Kingdom and pose a threat to our national security,” Cameron told MPs.  “We are clear in principle that what we need is a targeted, discretionary power to allow us to exclude British nationals from the UK.”

Cameron said as many as 500 UK citizens were fighting as jihadis in Syria or northern Iraq, and that represents the single greatest threat to the UK.  His ideas include giving the police the “temporary power” to seize passports at the border, something which currently can only be done by the Home Office under the royal prerogative. The police will only be able to revoke passports for 30 days and would be subject to judicial review.  Lib-Dem sources insist “it will not be possible for a UK policemen to withdraw a passport at the border on a whim.”

But Cameron went further, promising new “targeted, discretionary power” to prevent British terrorist suspects from returning to the UK.  And he wants to reintroduce “relocation powers”, which the government earlier abolished.  The Lib-Dems did not sign on to that idea, and even some Tory critics say it goes too far.

“I do share concerns that have been expressed that the suggestion British nationals, however horribly they may be alleged to have behaved, should be prevented from returning to this country,” said Dominic Grieve, the former Conservative attorney general up until Cameron's cabinet reshuffle in July.  “Not only does it offend principles of international law, it would actually offend basic principles of our own common law as well.”

Cameron offered to indication of how he would overcome Grieve’s objection.