If those potential extra British troops were engineers then ISAF might make some headway. Same with the McChrystal report - get thousands more combat engineers into the region and set them loose building infrastructure and shooting the enemy if they attack. It would surely allow NATO troop numbers to be increased while sidestepping many national caveats - putting people in there to build things but equipped to defend themselves against attack.
From Liam Fox's speech:
Consequently, when, where, and if possible in Helmand, we need seriously to start exploring ways of forming and utilising local auxiliary forces.
Auxiliary forces bring local knowledge and local ownership to local security. Something foreign troops will never be able to do.
There is already a pilot programme in Wardak Province called the Afghan Public Protection Programme that uses local citizens as static security forces for check points and road blocks and falls under the auspices of the Afghan Ministry of the Interior. Their local knowledge is a combat multiplier. They know when something or someone is out of place because they have lived there their whole life.
This is a new direction from the Conservatives isn't it? Almost daringly radical in it's pragmatism. A sidesteps of the issue of Pashtun recruitment into the ANA by pretty much recruiting the local militias our troops are being blown up by. Getting the radicals out of the picture will be the biggest obstacle I guess.
The auxiliary forces (Guardians) in Wardak province are something of a special case - it is a pilot project and not without its problems ...
A resident of Jalriz who did not want to be named said that most of the people now working as Guardians in his district used to belong to jihadi groups. According to this individual, those Guardians who have disputes with local people are misusing their new weapons. “Some of the Guardians who have personal problems with some people are going to those people’s houses and arresting them as Taliban.”
Political analyst Fazal Rhamn Orya agrees with the concerns of local people regarding the Guardians’ misuse of power.  According to Orya, the militias now being formed will be a problem in the future. Orya warns that, while the militias misuse their power against the local people today, tomorrow they will use their guns against the government and in time the government will not be able to control them. “These are not Guardians, they are the former militias. The Interior Ministry changes the name from militias to Guardians, but in fact they are not good for the future of Afghanistan. These Guardians will raise ethical problems; they will use their guns against each other in near future.”
Orya says that the Interior Ministry has no authority to build these kinds of militias and notes that there is no place in the Afghan constitution for creating militias. “These kinds of militias have had no positive result in Afghanistan history.”
Those are partial extracts ... you can read the whole piece at http://www.jamestown.org/
it gives a balanced overview. Nevertheless, I think Fox is grasping at straws if he wants to elevate a very early and problematic experiment into a core part of his strategy.