MI5 have been protecting some Islamics, but that was to do with their rather shambolic attempt to bring Quadaffi down. I don't think any of those guys has appeared on any of the lists that MI5 have compiled.
Abu Qatada has been an embarrassment to them for a long time, as they've never been able to arrest him and they can't extradite him to Saudi Arabia, or Jordan. A year or so ago the Saudis were putting pressure on them to extradite him, using an arms deal. That led to the last anti-terrorism bill, and he was one of its targets (made it an offense to operate against foreign governments - especially those who provide lucrative arms deals).
So the latest anti-terror bill was designed so that all these inconvenient terrorists could be dealt with. It made operating against a foreign government (mainly Turkey and Saudi Arabia) an offence. Prior to that, MI5 had (according to Abu Qatada - not the most reliable of sources) offered him a passport with an Iranian visa so he could get out of the country and be an embarrassment to somebody else. Finally they get their internment law passed, they can actually do something about him. Seeing his name was prominant on the list of terrorist suspects that they needed to get tough on, I think they really wanted to get the guy, as this would make them look tough to both the Americans and Saudis - and distract from their rather more embarrassing terrorists. The foreign office does not upset Saudi Arabia if they can possibly help it.
As for MI5's competence. Well they operate in a climate of almost total secrecy, with no accountability. They are still rigorously class bound and still seem to mostly recruit ex public school boys/Oxbridge graduates (these days I imagine it would be the ones too stupid to get into the city/law firms). From what one can find out about their intelligence over the last thirty years, it has been laughably bad. I still remember the Iraqi war, where they managed to arrest a bunch of students, and fail to arrest any Iraqi agents.
Going to ground in the UK (London especially) would be fairly easy for someone who had been living here. A large Muslim community to vanish within, much of it suspicious of the police/authorities. Whether he can stay hidden remains to be seen. For MI5/Special Branch this is another PR disaster, at a pretty bad time for them. If he'd vanished in October, they could have blamed it on week anti-terrorist laws, but now they've got them...
As for "Abu Hamza al-Masri", he's a British national (he doesn't operate from Brixton, but from the other side of London in Finsbury Park), so he can't be touched. I think his influence is greatly overrated by the media. I live close to where he operates, and their demos have less members than your typical Socialist Workers Party one. More entertaining though...
Cian
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