From the BBC:
“The existence of E Squadron is well known within the special forces community but has not hitherto been discussed publicly. It was formed five years ago to work closely with the intelligence service MI6, and is mainly involved in missions where maximum discretion is required, say Whitehall insiders.
Its role as a small, handpicked force operating with MI6 makes it the modern-day successor to the shadowy cell sometimes referred to as the Increment.
While the existence of teams of this kind is a gift for thriller writers looking to insert a hit team of hardened SAS men into their plotline, the reality of E Squadron’s operations has been a little more prosaic.
Last March’s debacle, in which six members of the squadron were caught in Libya, was highly embarrassing. The reason for their presence, escorting two people from MI6, gives a clue to the facilitating role they often play in foreign intelligence operations in risky places.
After 9/11, with major military commitments in Afghanistan and then Iraq, MI6 stepped up its intelligence-gathering in many places that had hitherto been off the radar or considered too dangerous.
It was often backed up by UK special forces, but the competing demands on them to support special operations in Afghanistan and Iraq eventually led to the creation of E Squadron.
According to special forces people, E Squadron is a composite organisation formed from selected SAS, SBS and Special Reconnaissance Regiment operators. It is not technically part of the SAS or SBS, but at the disposal of the Director of Special Forces and MI6.
The squadron often operates in plain clothes and with the full range of national support, such as false identities, at its disposal.
Whitehall sources suggest E Squadron was prepared to launch a rescue of a British citizen kidnapped in the Sahara in 2009, but could not obtain political clearance to do so before he was murdered by the hostage-takers.”