Army To Create Specialised Training Battalions To Counter ISIS
The British Army is developing new elite battalions to train local Iraqi and Syrian forces to fight ISIS. 
The Times reports that a number of specialised battalions will be tasked with these operations which are close in concept to the U.S. military doctrine of Foreign Internal Defense (FID), as carried out by special operations forces (SOF) such as the U.S. Army's Green Berets.
Unlike the Green Berets, or indeed, British Special Forces engaged in similar training ops, the new British units will only train and mentor the indigenous forces and will not normally fight alongside them.
While the Times' headline refers to a 'new SAS battalion', the reality is that they will be under control of the regular army rather than the UKSF directorate. The Times, does however speculate that the new battalions may act as feeder units for the Special Forces.
The plan was revealed in the Strategic Defence and Security Review (SDSR) released last November. Defining 'Joint Force 2025', an extract from section 4.48 of the SDSR mentions:
A number of infantry battalions reconfigured to provide an increased contribution to countering terrorism and building stability overseas. They will conduct defence engagement and capacity building, providing training, assistance, advice and mentoring to our partners.
The Army is developing the concept with a view to establishing the first couple of battalions, each with around 450-500 men, within the next 18 months.
More info / further reading
- 1. New SAS battalion will train foreign troops to fight Isis
(The Times) [paywalled}